You're not wrong that there's less pools, I think it's just somewhat due to a lot of miners not understanding how pools work. There's an unfortunate misconception that the size of the pool impacts your income, so they gravitate to the largest pool. Ghash.io is almost certainly evil (attacking sites by double spending in the past), but there's not much we can do about it unfortunately. Hopefully p2pool can eventually become larger and more significant, then the issue goes away somewhat.
