As you move up, there are more "soild TAgg" and Tight/Passive style players. So knowing how to deal with them (don't give up too much value, resteal/float a little, make it clear you're not going to be easy money) becomes more important. The fish tend to get a little more frisky, so inducing auto-matic bluffs becomes a key revenue stream.

As I moved from 100NL-short/200NL full to 200NL short, I actually tightened up a lot, read hands more and induce bluffs. You can't value bet as many of them to death and they won't fold to c-bets often enough to steam-roll, or at least you're not going to get away with it for very long unless you're comfortable playing big pots with air.