I think they are very therapeutic. It's important to purge. I find that I accumulate far to much clutter, especially with a young child. We are changing wardrobes often, whether he's growing out of it, the season changes, or I simply change my mind. Plus clothes don't hold up well. They fade. They shrink. They stretch. They stop fitting the perfect way they did when I purchased them. Or, I bought this, that, or the other with great intention just to later decide, after the receipt is long gone, I don't want it anymore. My son changes favorites every week. So, we end up with this abundance of "last week's" favorite toy, book, action figure, or whatever. We could quickly grow out of space if this stuff stayed around. I also feel you don't bring anything in without taking something out. This is a hard belief to live, but I'm trying! Plus, it's money in my hand.
I recommend a yearly garage sale to every family. It wards off the possibility of becoming a pack rat.
What put this whole garage sale thing on my mind is the loss of an old friend. I looked around my area and was sad. If I died today, my family and friends would deal with my death and the work to go through and clean up my things. If family came in for my service my grief stricken family would be forced to break out the trash bags and bins before they could entertain guest. Now honestly, I'm hoping they, and everyone I know(knew), are grief stricken! So although my place isn't a natural disaster it's purge, organize, and clean time! Now it's really, honestly, I promise, not that bad, but it's not the best it can be either.