So two things about the whole notion that "only Cosmic heroes can/should level all the way to 50":
One, that's wayyyy beyond the scope of what I was asking for at the start, and I have to think we're getting off track.
Two, you're saying that if I choose to limit my character's conceptual power level, I should also be satisfied with having (say) only one or two attacks, and a similar number of defenses or utility powers? That because of the concept I've chosen, I should also be restricted to a much smaller number of powers? And possibly giving up vital (under the current game design) tools like mez resist, or a self-heal?
Precedent suggests that every character, regardless of origin or player-imagined power level, can - as a matter of game mechanics - reach level 50. Going beyond that is the exclusive province of Incarnates.