For example lord personalities had a bigger part in the game then now, for recruiting them, getting them to follow you etc.
Or the whole courting experience, in Warband you needed to pick the right lord with the right daughter for the kind of game you are playing, then start oiling the wheels with the Lord in question, court the lady, maybe elope if you wanted, etc...
Now I just spawned as a scrub and bought my wife FROM A RULER and it was only RNG I got her (plus the money).
It seems to me that many mechanics have been "simplified", in Warband I was having my own kingdom at around day 1000 just for comparison
Some may say it is EA, I say that main features had to be in already and in EA we only had to find missing line of text or little mistakes, subtle stuff.