I personally love playing skirmish mode with my clan. The game has a good foundation to build upon but it is true that there's still quite a bit of work to be done in order to polish it.
Hence why it's in Early Acces.
I consider myself mainly as a MP player (coming from NW) but that doesn't mean I don't enjoy the SP and all the fun that comes with that.
MP however is what kept (imo) a large portion of the Warband community alive for the past few years whilst waiting for Bannerlord (e.g. the Napoleonic Wars dlc or mods like Full Invasion and Persistent World). With this early release, it is very noticeable that the developers are focusing heavily on SP as most of the bugs happen there (especially the sieges with AI are messy).
I wouldn't say "MP is dying" though. Have a little faith. I've been waiting for this game just as long as any of you and I'm willing to wait a little longer for all the fixes still to come whilst enjoying the game and the features it has atm. I'm sure there are others out there that share the same view.
Enjoy the game and see ya on the battlefield!