The issue is that many of us are vets who've done the story arcs to death on live. So the fun is trying out new sets and pushing them as far as they can go. If we had a steady flow of content throughout various levels people would probably be more inclined to stop and smell the roses. Unfortunately, that wasn't even the case when we had a full dev team. I don't think it will be the case here.
Also the fun of playing a living comic book is the power fantasy. The incarnate system fuels that and makes it possible for folks to do stuff that they can't normally do on the regular set up of the ATs. (Though arguably IOs do that more since they are slot-table for significant value in the 30s and up).
I think many folks who like the old traditional playstyle of COH might have to realize that most folks many not be looking for that any longer. And that more folks are who are more into the more slower style of the old days, may have to make some effort to form those types of teams.
I'm for more options for that. Like being able to set a team to only take folks with no incarnates (or even no IOs), or setting a cap on how many AOEs, etc etc. More options, not less.
EDIT: To be clear this isn't a D&D module where you as team leader is also the Dungeon master setting the limits. You don't know what builds folks will have before they join the team or even if they are full incarnated or just have alpha, or just have IOs. The only way is to tell people ahead of time. Many folks advertise in LFG that they only want this or that on the team or "2 spots left, could use some debuffers". That's fine. (I just like rolling with whatever within reason, but then I know that team is not for me and move on).