Well, I did a bit of extra research, and it seems it's my home router that is acting up. I can log in just fine using my alternative network, which is weird since it's a perfect clone. Sorry for the false alarm, I was mislead by the fact that it only seems to affect attnam.com. I'll try to figure out what's wrong.
On both my phone and my laptop, after logging out, attnam.com shows an error page. Can't log in anymore.
I can still log out and in without problems at work, so it might have been fixed last night... Will try again if I get home.
Maybe it was a technical consideration, for example that it's difficult to exclude the shop from random item movement during bones generation. That'd also explain the exclusion of the chest level. If you could find a way to keep certain areas from being included in the algorithm, I think adding bones on those levels would be no significant benefit to the player.