I think the question should no longer be "why is Taleworlds still not allowing custom servers?".
The question should instead be at what point did Taleworlds even reach the conclusion that any system other than custom servers should be the default one. Six months into EA, and more than a year since I played the closed beta I have no doubts that the whole thing is fundamentally flawed and will unfortunately never get better. There's just no coming back from this point.
Multiplayer of this game is so underdeveloped it's really hard to imagine what all the time went into. But think about the following, once TW did decide to produce Multiplayer as a component in Bannerlord someone had to:
- Decide on multiplayer's direction. What is the core experience and how should it look like?
- Decide how connections and servers will be handled. Matchmaking or custom servers? Or maybe both? Which has priority?
- Decide how equipment will be selected. Freeform? Forced presets?
- Decide which gamemodes will be the focus. Siege? Battle? Duel? Or the invention of new ones.
- Decide what progression will look like. Ranks? Badges? Paid cosmetics?
- Decide what core combat will look like. Skill based? Or perhaps not.
- Decide on a ton of other small, but important aspects like banners, player profiles et cetera.
Now think about those decisions above, and what direction was taken in Bannerlord's Multiplayer.
: All the wrong ones.
The old community evidently wasn't interested in this, and the 'new' MP experience is so lacking that no substantial new playerbase worth mentioning has gathered. Did anyone at TW really think you can make a bombastic new popular MP game with 5 maps in the pool or something. There's far better and far bigger generic MP games like this out there. This one has no soul to be unique, nor the content to compete with giants.
In the end the answer to all questions like the one posed in this thread is:
- Multiplayer market research and analysis(if there even was one, hard to believe there was one) reached all the wrong conclusions regarding what made M&B's multiplayer what it was. 90% of the good stuff from Warband simply isn't there in Bannerlord.
- The same research also reached wrong conclusions on what makes MP games good and popular in general.
- The Multiplayer team is too small and understaffed.
- The Multiplayer head designer has had the wrong idea from the very start.
Now it's simply too late for real changes, I'm afraid.