None taken, but do keep in mind that many of your reasons are also why a lot of modders support either one format or the other and often not both at the same time, at least not without help. I can sypathize with your situation but you also need to consider that it applies to those making and packaging the mods just as much as it applies to those using them.
From a modder's perspective, OBMM is not a friendly tool. With BAIN, I simply need to make folders named in such a way that the utility can process them as subpackages. I don't need a script even because BAIN will provide checkboxes to handle installing the archive without doing a thing - bonus being the USER doesn't have to do anything special either.
BAIN even provides a way to do project and release management with simple clicks of a couple of menu options.
Honestly, I don't even know how to make OBMM create a package from a bunch of loose files stored somewhere on the drive. I poked around with trying it once or twice and determined it wasn't worth whatever hassle was involved and so I simply stuck to doing things manually until BAIN came along and filled the hole.
I'd love to know how I can instantly, transparently, seamlessly and completely switch all control of installed mods from OBMM to BAIN, including shader tweaks like Timeslip's nighteye shaders and Detailed Terrain. AFAIK, BAIN has no idea WTF I've done in OBMM and this is impossible. Correct me?
Instantly? I don't know about that, but if the archives you're dealing with are in a form OBMM can install, generally you can just drop those same archives in and BAIN will know how to handle them as well. Unless the archives you're using are all in the .omod format. You do have to copy them yourself, it won't just find them for you.
BAIN doesn't handle shader installs though, so that's one area where OBMM still holds sway. I don't know if there are plans to have BAIN do that.
The one thing BAIN handles better is what makes it the more ideal choice. Resource conflicts. BAIN keeps detailed track of which mods install what files and will unpack the correct versions of any overlapping resources if a mod is removed that shares files with another. OBMM doesn't keep this sort of detailed record and you will end up using whatever the last copy of something is, even if that happens to be a buggy older version of those files.