Batman in animation is basically of two periods: before and after B-TAS. Before it was pretty straightforward adventure with next to little nuance and character---essentially generic Saturday morning kids' fare. After the debut of B-TAS we got a much more complex depiction of Batman and his world, and it's been generally consistent in overall approach since even extending into the series Batman Beyond.
I'd put the transition between periods a few years earlier, around 1985. The last season or two of Superfriends
in the mid-80s, under the Super Powers Team
title, had Alan Burnett -- the producer of the DCAU and subsequent Batman/DC productions -- as its story editor, and he handled Batman in a way that was much closer to the comics of the '70s and '80s, a more serious character and a master detective who was always the smartest guy in the room and five steps ahead of the bad guys. He was still a lighter Batman compared to what came later, but handled more seriously and feeling more authentic to the comics. (This was the third and final series in which Adam West played Batman, and the first time he'd played it seriously, which he did reasonably well.) In particular, Burnett wrote an episode called "The Fear," which was the first ever depiction of Batman's origin story outside of the comics, and which felt in many ways like a prototype for B:TAS. (Indeed, I think I've read that it actually was a backdoor pilot for a Batman series.)
Alan Burnett is surely one of the people most responsible for the maturation of Batman in animation. Timm and Dini get all the credit for B:TAS, but Burnett was their partner and predecessor in the process, and his resume as a producer includes the entire DCAU, The Batman
, and the DC Universe Original Animated Movies series (as well as Krypto the Superdog
There might have been some difference with the other Batman series, but I can't speak to that because it never interested me. Even so that depiction doesn't seem to have had a lasting impression because the DCAU films harken back to B-TAS in overall tone and depiction of Batman. The other exception is The Brave And The Bold which has a somewhat more humorous sensibility. And while enjoyable TBATB still aren't influencing the DCAU features.
I don't see why you'd expect an influence. The point of the DC Universe DVD movies (which are DCU, not DCAU) is to tell standalone stories inspired by the comics, each in its own distinctive style. They're created and marketed for a different audience than the TV shows -- older-skewing and more familiar with the comics. So there's no reason why they would be the same.
And I don't agree that the DCU films are specifically imitating B:TAS and the DCAU; it's just that they have the same producers, Timm and Burnett. They aren't specifically trying to copy their past work. They're trying to make original movies that are inspired by the comics. But since they're still the same people (plus a decade or two more life experience), there's naturally going to be a similarity in their creative voices and styles, even when seeking to do something new and different. The Batman
and The Brave and the Bold
are different because they're from different creators. The Batman
had producers Burnett and Glen Murakami in common with the DCAU but owed largely to Duane Capizzi and Jeff Matsuda. The Brave and the Bold
was the vision of James Tucker and Michael Jelenic. Most of those people are DCAU veterans, but they have their own distinct styles and approaches.
So the similarities and differences you're talking about don't show anything about how much of a "legacy" the respective shows have left. It's just a matter of who produced them.