Strongholds as implemented in BG2 would be easy for Larian to put in the game, and the "complication" and "lack of dev time" is simply not a good argument against it.
In all of the stronghold quests in BG2 there is an elaborate quest that leads to the stronghold being offered. However, this quest is open to all!
For instance, Nalia De'Arnise will invite <charname> to liberate her family keep from invading trolls, regardless of <charname>'s class. After the liberation, she will ask <charname> to assume possession of the keep **IF** they are a fighter (or barbarian, monk, or blackgaurd). There are a few minor quests that ensue from this, but the bulk of the interaction with this keep is during the liberation, which ALL classes get to participate in.
Likewise, all characters have an opportunity to rescue Haer'Daelis from the planar prison, but if <charname> is a bard then they will be asked by his troupe to manage the Five Flagons playhouse, which again, leads to a number of fairly short quest interactions. Again, the bulk of the quest is the part that everybody can do.
This pattern repeats for all of the strongholds. The fact that these quests were quite popular with the players seems somewhat odd when you consider how little needed to actually go into making them... but that just stresses again that there is no reason that Larian could not do this.
