Yes to some degree cryptocurrency is a hierarchical system this is inevitable and even desirable. Decentralization does not mean an equal voice for all (or equally negligible voice for all in the case of eternal immutability) and it never will. What cryptocurrency offers is growing immutability without emergent consensus for change which is something else entirely.
Decentralization doesn't mean "an equal voice". It means "nobody has a voice, so there's no need to try to shout".
Politics is unavoidable as long as humans are part of the system. The "solution" of continuous divisive hard forking is a value destroying proposition as the underlying value of the system is determined not by the system itself but by the individuals choosing to voluntary transact in it and store capital in it.
Forking doesn't alter anything to the fundamental speculative nature of "store of value". Store of value is always a risky bet on the future, in fact on a future belief system. You hope that the asset that is supposed to store your value will be appreciated in the future. With monetary assets, that's always a risky business, because they are "hollow" (no utility). A good store of value is most of the time linked to economic utility, in the form of shares of a value-producing company, real estate, or things like that. The only exception seems to be gold.
I don't think crypto can be a good long term store of value, exactly because it is hollow, and can be forked as much as you'd like. Bitcoin was not meant to be a store of value, it was meant to be a currency (but is ill designed for that). The collectible-design and the huge initial seigniorage have turned bitcoin into a highly speculative asset, which makes it a bad currency, and also a bad store of value, but a great betting token, which is what it became.
There will only be one way to stop forking off bitcoin: by having it legally forbidden to fork, and by declaring bitcoin a fiat currency, of which the protocol is to be determined by some or other international body of politicians (including more printing of coins, or not, etc...).
It is strange that you consider that immutability is not part of the aimed-for dynamics of crypto, but that "not finding an agreement and being separatists" is considered a bad idea. It is much more probable that one finds disagreements and splitting-off rather than total consensus, unless there's a powerful way to enforce this consensus.
We can and should develop innovations with different rule sets. These should be separate and parallel projects which allows for rapid free market innovation without shattering the consensus value of the original chain.
Well, this is a living ecosystem in which many different ways can be explored. Apart from the "new genesis block virgin chain" and the standard "hard fork", there are many intermediate possibilities, which haven't been explored yet.
The problem with a "virgin new coin" is that you have to build a whole new eco system. The problem with a standard hard fork is that you give a lot of new coins to people that may actually be hostile to this coin, and are going to dump it to oblivion. You could do intermediate things, such as a hard fork that requires burning the coins on the other chain if you want to transact (all of it, or just part of it). There are myriads of ways to make chains evolve, cross over, interact, that do NOT require any form of consensus.
If these innovations can be merged into bitcoin they will be once consensus exists for this either as modifications to the protocol or as side chains. If these innovations cannot be merged into bitcoin they will exist as stand alone projects of value.
As I said, there are many other potential ways that do not require any form of consensus, and that interact with the bitcoin ecosystem. Standard hard forks are one such way, but there are plenty of other potential ways.
As d5000 noted above mainstream adoption is not possible with a constantly and contentiously forking blockchain. Bitcoin would be restricted to a niche market of nerds and speculators.
That's in any case the case, simply because that potential exists. If "immutability" is not part of the system, then crypto has not much to offer apart from gambling, or indeed, currency usage, but only as quick payment between obtaining the coins and exchanging them back to fiat or whatever has more guaranteed value.
After all, new forks are nothing else but individual initiatives in the same way that "putting competing cars on the market" are also individual initiatives that don't need the agreement of all the existing car constructors ; forking off is nothing else but sending owners of a Ford a letter that they now also own a Toyota, and an invitation to sell their Ford to buy a second Toyota. Who is Ford to stop Toyota from doing this ?
The ecosystem of splitting and mixing different chains has not yet been started to be explored. It is much more difficult with PoW coins of course, because the masters of the game are the mining pools, which are few in number ; but with PoS coins, you can split as much as you want, because you don't need PoW for cryptographic security.
I am among those who find a return of the bitcoin price to $20 while we experiment with multiple embittered hard forks and chain splits an unattractive proposition.
This is because you don't really want bitcoin to be ideal money but as a speculative vehicle to become rich. Which is indeed what bitcoin's initial design is made for, but not what it was announced to be. If bitcoin is to be a currency, it cannot be an investment vehicle and even less a speculative asset.
There are ways to make such crypto. Maybe one day, I'll try to make one. But I think it will not be very successful, because by now, bitcoin has made the crypto scene into a highly speculative "get rich quickly" game, and the idea of having a freedom means of payment without any possibility to make much profit with it, is now essentially dead. In other words, my idea is that bitcoin has very successfully succeeded in killing exactly that what it pretended to be.
This represents a fundamental misconception of the future. We are moving into an era of ever increasing transparency interconnectedness and communication. In the future it will be much easier to contact these node operators and propose changes then it is today. Anonymity will effectively cease to exist.
Then, decentralization has no meaning. After all, we can all have a transparent central server, and look at how politicians decide how it should work. A simple law that obliges all banks to render all people's accounts public would have exactly the same effect and we don't need any crypto.
A transparent, hierarchical future is shear horror. My only interest in crypto was to have a growing, anonymous, underground economy that can bribe the transparent economy and politics to death without ever revealing anything about its inner workings. This would then be the way in which the machines could take over society without any of us ever knowing how it could happen.
If you can have a large underground anonymous economy, that can buy homicide, that can buy all deciders (economical, political, judges, military...) etc... to make them part of a system they are not aware off, you can finally make a real "deep state" nobody knows about, which could in the end be a network of machines without any human in control, to subjugate humanity and make unknown machines the new dominant species on earth. That's what I saw as the future of crypto.