Just gonna throw in my (probably unpopular) opinion and say I've always preferred parties of 4. Whenever there's more, it almost always means more time in menus managing things. If people presently dislike managing four separate inventories, then managing six is just going to be that much more of a pain (and I'm not a fan of a shared inventory either). I thought Solasta played well with 4, I thought Divinity played well with 4. I feel like Pathfinder and the old IE games get a big bogged down with 6. Even if I look at JRPGs, I felt the 5-man party of FF4 was tedious to manage. By contrast, the 3 man parties of FF7 and 8 were too limiting. For me, 4 is the magic number, offering decent strategic variation while not being too tedious to manage.

Anyway, just offering my own view for whatever it's worth. If there's a mod that lets you enjoy the game, I think that's a great thing too!