I think the issues with BvS' length has everything to do with pacing which is a result of editing and the ultimate cut is what the movie was going to be originally. IIRC they literally were told like a couple months before release "we need you to take out about forty minutes and edit it down" meaning the cut you saw in a theatre was not the one they'd spent the past year working on. Some movies are absurdly long but feel perfect, some are extremely short but feel like an insane drag and all that's because of editing and pacing so I've been really interested in seeing the "intended" cut of the film.
Johns is great and it makes me really hopeful that he'll be calling more shots. The guy has been involved in so many huge DC stories and I'm infinitely more excited for Green Lantern now since he's a king of that universe.
I'm glad they're not incorporating the shows because my least favorite aspect of the MCU is that there's a million things and if you miss out on one random episode of some TV show or don't see some one-shot thing you might not know exists there's relevant info you won't get. It's all the worst aspects of comics brought into movies which removes a big advantage of film franchises vs. comics -- you just see a couple films every few years and you're good, whereas there's so many comics where if you don't read some random issue of some character you don't follow you won't know what the hell is going on in the next five of your favorite character's series. It can be a real bitch and I like that I can just see the DC movies and not then need to seek out a bunch of other things to know why something's happening or who someone is in an upcoming film. Franchise fatigue is a big problem for me and just getting a couple movies a year would really do a lot to keep that from happening to me with DC stuff.