The truth is Dwarfpool has been a lot more stable than any of the other pools in my experience. If the other pools can keep the same uptime and offer similar features as Dwarf, then you might see more people spread out. Also I thought the risk of any kind of 51% attack was mitigated by POS? They would require a significant amount of the available coins (stake weight) in addition to controlling 51% of the network. Am I wrong?
I don't think only Dwarfpool has been "a lot more stable". I have used MiningPoolHub since several months ago, and never experienced any significant downtime or communication issues at all. Also other pools managed them quite well except the period of that pos bug and forking issue, but it was not their fault.
Dwarf's no registration "feature" seems good, but other pool's registration also has some advantages too.
I am monitoring all pools' status every 2 min now. I will post it on jpcpal.com soon.
Luckily JackpotCoin is pow/pos hybrid, so it may be less risky to have 51% control either on PoW or PoS, but it does not justify that we can ignore it.
For better stability and security, it is always better to distribute hash power.