I really like these version of the Titans than the comics do (though Dick eventually went back to being Nightwing and Dick seems better off as Nightwing than Batman). Doesn't really matter, because this is awesome! ^^
The world needs a Batman, and compared to the others attempting to be Batman at the time, Jason murdering everybody, Tim nearly getting killed by Jason, Two-Face running amok, Dick as Batman was the best solution.
Dick did become Batman, twice (First time, when Bruce broke his back. The second time, when they all thought that Bruce died). He even stayed as Batman when Bruce took back the mantle and they both fought along side as the Batmen, but he eventually went back to Nightwing.
Also, you forgot about Damian on why he can't be Batman and the fact to prevent Hugo Strange from becoming Batman.
Yeah.. Completely forgot about Hugo... But Damian could be Batman... He'd probably be more like Green Arrow than Batman though, only killing when it's a life or death situation, rather than just rushing in murdering everyone in his path.
I personally think his pants would look better if they were just black, same with his gloves. The shoulder pads draw the eye to much so maybe just red. That's just my opinion though. You have your version of Wally I have mine I guess.