Why do the Ikko Ikki behave exactly like the other clans in Shogun 2? They were not so much a clan as a loosely aligned group of peasants and low nobility which admittedly I have no idea how the game would portray properly but it could have been really interesting.
To put it bluntly, Video Game Historical Revisionism. In finer terms, why go through all that trouble to "portray properly" in gameplay terms when they don't exactly get love from fellow clans and typically get wiped out quickly? They already get unique units, including special priests and a lack of metsuke. Throwing an overhauled government system on top of all that would be very frustrating and possibly too much for some players.
This period of history is subjected to a lot of Common Knowledge. The Ikko Ikki really weren't all that different in terms of how they operated, equipped, or organized then most small clans. English translations also really like to label nobles as "Samurai" even though, at that time point, "Samurai" wasn't a very well defined term. A lot of the "Peasant" vs "Samurai" vs "Ninja" conflicts were typically against two factions that functioned very similarly and got relabeled a few hundred years later to fit into these class roles.
Why is the AI so terrible with diplomacy in this series (at least in Rome and Medieval 2)? Half the time they're making either ridiculous demands or stupidly obvious bluffs. "Pay us an obscene amount of money or we will continue this war that we are clearly hilariously losing." Is this a case of poor programming or am I missing something?