In my opinion it gives a build more character, although I use clutter in moderation. I feel that it is important to find the right balance between aesthetics and functionality. The amount and kind of clutter I use also depends on a sim’s personality and the overall narrative. I don’t think there is too much clutter in the catalogue, although I would like an option to expand it to get a better overview of the contents. I don’t like this tedious scrolling.
As some folks mention here, I very much dislike builds that have not been playtested. I may choose to edit the lot, but as a hotheaded sim I tend to lose my temper and will delete the build from my library pronto if it proves to be incredibly messy and buggy. I don’t care how amazing it looks. It needs to work.