It's not about hash-power, it's not that hard to make a merged-mined alt-chain which will have almost as much hash-power as Bitcoin itself.
J. R. Willett explicitly mentioned that it is important to build disastercoin on top of Bitcoin and let them interact.
Well, if Bitcoin allows one to use other people's resource, either it is flawed, or your understanding of what it is is flawed.
In any case, to make decentralized exchange useful, you need it to be integrated with a powerful cryptocurrency.
Let's consider an example: suppose Freimarkets got implemented overnight, and some startup offers its shares for sale through this system.
I want to invest $100k, so I buy $100k worth of freicoins... Ouch, it's not so simple: that many freicoins are simply not available on exchanges, and trying to buy them would move the price, a lot. So it isn't even funny.
Thus a barely functioning decentralized exchange which works with bitcoins is more useful than a perfect decentralized exchange which works only with some obscure alt-coin.
1.) Its always been about hashing power. The alt-coin method of establishing your own blockchain was discarded from the outset, because the lead dev was worried he wouldn't get profitable fast enough.
2.) Bitcoin can be abused like any other resource, and while its utility exceeds most cases of this abuse, it doesn't detract from the fact that the abuse occurs. Ignoring this is the usual M.O. for Disastercoin participants.
3.) You then make the contradictory case for an alt-chain's usefulness. If the principle is fundamentally useful, why wouldn't more miners support it and users participate? Having to hook into Bitcoin and co-opt hashing power just means that there's a real fear that any other way wouldn't yield any interest, so they shove it down the miners throats instead.
(And users, by extension of full verification node resources.)4.) You then setup a nice little straw man in the form of
"all alt chains are obscure, therefore"... riiiiiight. The real issue here is this - The ONLY reason Disastercoin is co-opting Bitcoin is because they are afraid of it not succeeding otherwise. Of course they ignore the fact that failure, or
"tail risk" still exists regardless of their implementation. Again - if the idea has ANY MERIT AT ALL, it would survive just fine as an alt-chain.
As for other competitors, why should I bother? The information is out there and available, just look for it.