Power creep is something that happens within editions not between them. Besides, I don't think the comparisons are meaningful. How could you condense the epic level rules, that reach to infinity, into ten levels meaningfully? They are different systems with different parameters. It seems like Epic destinies, when they reach their end, have drastic transformative consequences. There's no advancing from there, not from a personal, inherent power standpoint. That concept just doesn't translate meaningfully from 3.x.
Edit: In other words, 3.x is "turtles all the way down." While 4th Edition is entirely contained in one turtle.