Bear in mind I have no saying in this decision. However, I'd like to drop a few thoughts. First because it's an interesting subject. And second, but most importantly, The Coop has always been friendly and approachable. And I wish him the best!
As someone like you who is known for using sigs as means of showcasing visual prowess, this change feels like cutting down a long time beloved tree, doesn't it? Still, you're very talented. And I do hope your involvement with DeviantArt and alikes has been filling the void OCR couldn't fill for you anymore.
Unfortunately, it's been years since there was a present and consistent sig making community on these boards. All you could witness recently were a bunch of untouched "June is Boss Month" sigs and such, which honestly gives the forums a sense of lack of updates and abandonment. Sure, sigs used to be a huge thing in the past. But you can't say they've even been a thing in the past 6 years or so.
You're aware that in the past, there was no such thing as custom avatars. Everyone had to choose one from a curated gaming/anime/TV-film collection. But now not only you can have your own custom avatar (which can be a closer artistic expression of yourself more than ever), but it can even be animated if you wish. By this perspective, don't you feel this is a fair trade-off?
But you do post in another forum where its community, which fostered sig culture like no other, grew older and don't use sigs anymore either. And that didn't stop you from being a part of it. In the end, our primary way of strengthening relationships and camaraderie is the exchange of thoughts. Although I admit making new friends here throught my own sig skills, this alone could not provide such strengthening.
You're right. This is a music site. And that's how you've been labelling it all the way. Which means it's not a sig site, nor a visual arts site. Sigs do, however, bring memories associated with its posters and to a certain period in time you've been here. With that in mind, newer posters won't be able to have the experience of shaping said memory like you or I. Yet, this is a completely new community now with these social media platforms (come join us in the OCR Discord server, Coop!) on the side. So OCR members might be shaping other kind of experiences lately and sigs haven't been a part of it. I'm as nostalgic as you, though. And I'd love to witness a new bunch of artists making neat looking sigs to new other regulars. It would give me warm goosebumps!