And I've said it again, what can they learn? Mod support. Even CDP has started to follow the mod support bandwagon over the years.
Also stop using an action adventure game as your argument, jesus christ.
The thing is, Bethesda can have mod support because they are still using the venerable Gamebro engine (which is also a reason why the game doesn't look very good and has tons of bugs that were already present in Oblivion). They haven't changed engine in more than 10 years, and I'm willing to bet that it's because modding Gamebryo is easy and, more importantly, there is less third party software that Beth would have to license for an arm and a leg.
By contrast, Bioware is now using Frostbite. Which looks much better (hair aside admitedly) and has less bugs and collision issues, but EA has made it clear that modding is more or less out of the question because it's hard and the bevy of third-party software at work means its probably very expensive to implement.
I think this idea that devs just need to find their magic ''make the game moddable'' wand and wave it at their game in order to make it a modder's dream needs to be dispelled. Not saying you think so, but it seems loads of people think its simple when it very much is not. At this point I'm pretty sure it is out of Bioware's hands at any rate.
And while I like modding a lot, I think I prefer games that are functional on release. FO4 is, to me, barely functional. It crashes, it takes ages to load textures, it stutters then goes back up to 60 FPS fo no apparent reason, it's awfully optimized for how poor it looks, it has loads of bugs and collision issues, and whenever it rains my screen always become a blinding white that makes the game utterly unplayable forcing me to hide indoors and wait or fast travel. I had bugs with TW3 and DA:I on release too, but nothing on that scale.
Cripes, the two aren't mutually exclusive. To keep an RPG case, TW3 has modding support and wasn't a cobbled together mess on release. I'm tired of Bethesda being given a free pass because of mods.