The quadratic disincentive Bytecoin&forks does is very bad, there is no upside to it. It doesn't achieve the advertised end, it encourages people to pay miners directly instead of fees, thus improving the position of large well known miners. (If you just mean using a median-controlled limit— sure, but thats a old proposal in these threads that has nothing to do with bytecoin. I would point out that an explicit desired size is better than an actual size in that calculation, to avoid miners needing to pad their blocks or omit transactions they could have included just to express a desire for another limit).

Sadly there is still no proposal that I've seen which really closes the loop between user capabilities (esp bandwidth handling, as bandwidth appears to be the 'slowest' of the technology to improve), at best I've seen applying some additional local exponential cap based on historical bandwidth numbers, which seems very shaky since small parameter changes can make the difference between too constrained and completely unconstrained easily.  The best proxy I've seen for user choice is protocol rule limits, but those are overly brittle and hard to change.

Petertodd and jdillion previously had a POS-ish voting proposal that might be interesting... but any of that family seemed complex to implement. The notion there was that signers in recent transactions, selected by non-interactive cut and choose using the block hashes weighed by coins days destroyed, could reveal signatures of block-hashes after their transactions in order register approval for increasing the block size.  Since miners can always decrease the blocksize unilatterly and would usually be in favor of increases, and they can censor users— so if the users consent is one sided and needed for increases, and the protocol is constructed so that users can't be forced to give consent in advance except by giving up their private keys— this actually has a fighting chance of keeping the users in the decision.  But there are a lot of free parameters in how it could work... and giving a majority of coin holders a voice is actually a pretty poor proxy for doing something smarter:  Democracy is still an oppressive system which forces the will of some onto others, and those holding the most coins might be large corporations or goverments who benefit from centralization, still better than just handing the decision unilateral to miners.