I see what you guys are saying about improving on existing skills, which can sort of put it in an RP context; except often the new power is markedly different from the original.
However, I think LowSpine echoes my feelings well. By level 13, you're pretty experienced with the game. Having 10, or 12, playable power options available isn't going to be overwhelming (not counting at will/utility). Being limited to 8 for the majority of your gaming career up to level 30 to me seems very arbitrary.
Starting people out with 2 at-wills, 1 encounter, and 1 daily is great. People learn the basics in the first few levels. But as you approach epic levels, I think the player should have more & more options available in their bag of tricks, and their character should be powerful enough (no pun) to display numerous forms of skill and prowess in any encounter.
If every difficult encounter means you blow 4 encounters, a couple dailies, then it's at-wills for another half hour of playing, that seems to me that the game is cutting you short. Those at-wills, which are certainly useful, in my opinion should eventually become last-resorts which you only use at the end of a long, tiring battle in which you've exhausted all other resources: not something you turn to after the first few rounds.
Obviously I haven't, and few people at this point have, run a character from 1 to 30. In a year things might look different. But looking at the road ahead from the start line, it seems about halfway on things really start slowing down.