Look at DotA: built from senario editor in warcraft3, blizzard gave the tool and players imagination built one of the most played PvP concept since a few years.
Dota has predefined heroes with 4 skills (well, most of them) each. And that's the idea why it's so popular and rather balanced, generally. Dota would be broken, if you could mix hero skills. Imagine Traxex getting any additional damage buff and stun, or lich getting an Earthshaker stun, or whatever. So you're precisely missing the point, and Dota 2 is a perfect example of why NOT TO get custom hero creation. Especially considering, that in D:OS2 Arena you control more than one character. For example, I can already say that characters with teleports, stuns, and adrenaline would be imbalanced. And that's aerotheurge and scoundrel, quite close to each other, rogues already have shocking touch anyway. At the same time, fire magic wouldn't be added to the mix at all i think, because who needs fire, when it can be blessed and turned against you in one tick, and when you can get stuns and freezes. Etc.
So heck no, no customizable heroes, onli predefined ones - with a wider selection of them, of couse.
