I used to love completing full waves and getting obscure characters and all that, but times have really changed. I, too, only collect what connects with me- comic-wise, I really only get Spiderman and X-Men figures, and even then only the ones I'm really familiar with (I realized a few years ago I really only collect based off the 2 animated series I watched as a kid, so if they didn't appear there, I usually don't gravitate toward them), and most MCU stuff. As such, most of the BAFs, unless they're centered around any of those 3 things, I usually don't keep, let alone complete. In fact, I got rid of a bunch of random BAF parts the other day that I'd been holding onto for years for whatever reason and knew I'd never offload. I can also agree with the argument that, since the focus is on the BAFs and they often feel a little more deluxe, the figures in the wave can often feel like they get the short end of the stick, which I'd love to see change.
I don't know what the best option is- it's nice having that little extra bonus; on the off chance I actually complete something I don't want, I can always sell it to make a little extra money back. But at the same time, I'd love to not have all these extra parts I'll never use and are just taking up space. At least with extra accessories, I can usually rework them into other figures, but with BAF pieces, they're tied to that one thing and that one thing only. Diorama pieces, I feel, can usually be worked into a handful of displays, and can incorporate at least a couple figures, thus saving a little space. I don't know- maybe I'm just craving diorama pieces because we haven't really gotten any in so long, and the novelty would wear off after a while and leave me wanting BAFs again. That's why I've kind of grown to appreciate the retro cardback figures- not having to worry about extra anythings and just enjoying the figure.
Maybe removing the BAF concept and just releasing a couple deluxe figures a year, however obscure they may or may not be, in slightly smaller numbers? Or a made-to-order type thing?