It's not like it takes a tremendous amount of game data to make the rooms the same size as the upper/lower rooms it just doesn't make sense to me, feels like a very blatant, nonsensical downgrade
I get that some people like keeping them small, but there should really be an option to upgrade them! Also, this might just be me but I hate the 2 rectangular rooms and I wish there was an option to change that too lol
I've only opened up the back and right rooms, so far (gotta pay that loan off!), but I kind of like the different sized rooms. It makes it seem more like a "real" house, since my house has multiple sizes. I get that people want to decorate to the max, and I love that aspect of the game, too, but I'm looking at this as a means of being more creative in what I do with the various spaces.
One thing about the side rooms being smaller is that I like that you retain your windows in the main room. I hated losing them in NL.
I guess I'm in the minority here. I like the different sized rooms. Consider that rooms in most houses aren't going to be the exact same dimensions. I like the different sizes and shapes, it means each room isn't going to look like the same box