I am basically at this point as well. Too many one tile hallways. Too many routing issues. Too much non-functional clutter. Other than Maxis, I'm at the point where I'll usually only consider shells because I prefer designing the space for my sims. I've also been improving my roofing skills and I am fine with building more.
I've sometimes added a gallery lot and then pulled it out because it either didn't fit my space or more often, it had bad floorplan layouts. Generally, they have tiny hallways and tiny rooms that are overcrowded with stuff. I've also run into problems with excessive kitchen clutter such that the stove would malfunction. I had to go in and take parts of the kitchen out to get it to work. I mean, I can do that, but I end up preferring to build for myself.
