First of all, prestige levels were originally introduced so people could keep playing with their favorite heroes. Max level? Prestige and start over. No need to bench a hero just because there's no more progress. And yes, I know there are several ranks of prestige already, with Cosmic taking a long time to get.
But here's the thing. Or things. There are some heroes that are somewhat boring to play at low levels. Some really takes their time to get going. Also, prestiging can feel a bit... underwhelming at times. "Congrats, you reached max leve. Now we're gonna reward all your hard work by resetting your entire process. Yay?" On top of all that, leveling is very quick now. I just finished chapter 1 at level 24, though with the hero synergy XP. Still, leveling is very quick now.
So.... here's my idea. When we reach max level, what if we could unlock an "alternate" cosmic prestige? This can be access simply by buying an "Alternative Ancient Gourd of Prestige" from Clea. This one will function in most ways like regular prestige, but with a major change: You stay at max level. This means that the story mode is reset entirely, but you don't get any rewards from it other than the XP. You already got the skill points, artifacts and all that on your first run to max level, so no need to give it to us again. The only thing we need is the XP. What it does mean is that you can now enjoy playing through the story mode at max level, fighting enemies that are your own level the whole time. In other words, all the hard work getting to max level is now rewarded by going through the story and keeping all your hard earned skills.
Of course, the new prestige level would take a long time to get. I'm thinking it's roughtly the same as cosmic prestige. Then, when you finally get to max level again, all you get is a new color for your name. Pink, for instance. But if you already have cosmic prestige (or get cosmic prestige after the alternative way), you get a new color for your name. Gold, perhaps. Or black. Multicolored, even. Dunno, doesn't matter. Or they could even let us pick the color we want on our name (for color coordination etc) like we select titles?
The whole point is that once we hit max level, we can prestige the hero and do everything all over again, yet we get to keep the skills and levels. :) You finally got the hero to max level. Now go out there and really enjoy playing him or her. :)