What you are explaining here is the longest chain, without the word valid. While the longest chain is usually valid, it's not necessarily so. Validity is decided by the nodes which are the economic majority. Miners are incentivized to follow the economic majority, but they are not required to do so.
I don't think that's how it works at present. As I understand it, the longest chain is decided by the software, the user has no way to determine which chain the software follows. Might be wrong, but it's a debugging feature if it exists at all.
The longest chain is decided by the software that the majority of miners choose to run. It is the users that determine which chain the software follows because it is the users that choose the code in the form of what type of full nodes they decide to support, the same is true for the miners.
This might be the aspect of the Bitcoin network you are failing to take account of, the human element. This aspect of the Bitcoin network does not fit neatly in the discipline of computer science, a multidisciplinary approach is required in order to better understand the various dynamics that make up the body politic of Bitcoin. From game theory, psychology, politics and economics. Bitcoin might not always be entirely rational considering that it does reflect the will of the economic majority.
You're asking to let the users play with any underlying parameter or constant of the system that they so choose, "because liberty". The equivalent argument transposed to the original hard money, gold bullion, you'd be making your case to the underlying nature of the universe. Not so easy to address.
In computing, you're literally creating your own little universes every time you write some new applications. You decide all the rules, how many dimensions there are, which way's up etc. The idea of having competing multiple rule sets, operating at a fundamental level of the software, is not a good plan. The participants in the universe have to adopt one set of rules or another, and whichever do so, cannot interact predictably with those who choose differently. Too much unpredictability of outcome.
If you think your vision for a Bitcoin competitor is such a good idea, go and get your own hashrate to subject it to. Your agenda is to change a system that doesn't want your proposal, and you just won't go away. You're in a minority, and a decreasing minorty at that. The real plan to scale Bitcoin up responsibly is now underway with BIP 65 rolling out. Get your own coin.