Really? 160,000 downloads of a SINGLE mod on a SINGLE mod website somehow proves that most players don't use mods? The opposite is true. ModDB is around the same size as Nexus and the Steam Workshop is hosting mods now as well. The workshop is point and click to install, so there is no barrier whatsoever for someone of any skill level to use mods. Floris isn't even the most popular; that would be A New Dawn or Silverstag IIRC which are both very impressive improvements to Native. Not to mention that a lot of mods, Floris probably included, use an external download hoster because Nexus and ModDB hosting is lacking.
You completely missed my point about the expansions if you think it was invalidated by saying that they were made by modders. That is exactly what I'm talking about. Taleworlds has been putting minimal effort into this game ever since the day they released it. Patches were few and far between, and the fact that they would endorse the "expansions" shows how little regard they have for their customers. It's why I fear Bannerlord to be little more than a new money printer now that Warband sales have finally dropped off. If they could outsource it to some nameless 3rd party they surely would.
You're a fool if you think another studio couldn't make a competitor to M&B with only small effort. There are very few real design hurdles between a regular RPG and a medieval game like M&B. Bethesda swaps between Elder Scrolls and Fallout using the same team and the same engine with no issues whatsoever. If Skyrim's engine were overlayed with M&B's party system, management, and instancing it would blow M&B out of the water.