I have no doubt that you are correct the TSR workshop is including more resources than necessary. However I believe when CC in sims3packs are installed into the DCCache files the CC is compressed again. The copies stored in the Downloads folder don't affect game play and can be moved or deleted. And it doesn't seem that the extra "junk" included in the files affects playing --- or at least it hasn't in my game. I'm not saying that they shouldn't fix it so the extra stuff is removed. If the stuff isn't necessary it shouldn't be in there.
I love your stuff, and I download it, and try to use it, but I always end up taking it out because it slows down my game too much. My DCCache folder is about 3.5 gigs (filled with ea-store and other CC from sims3packs) and the game runs fine -- starts in about 45 sec and uses about 1.5 - 2 gigs of RAM during play. If I add even a few package files to my mods folder (totaling less than 150MB) it quadruples the loading time and ups the amount of RAM the games uses by at least 500MB. And yes, I have checked the files with the Dashboard tool and used process monitor to look for problem files. Neither, has found any problems.