Now, before I start off, I'm not going to specify my AJ status, to not start a war.
Either way, when you preview dens, they are HUGE. The underwater sand castle den (or whatever it is) and Greely's Hideout are some of the largest dens I have ever seen, and though Greely's Hideout is an older den, why does it seem like newer dens are getting bigger and bigger.
Cosmo's treehouse, rereleased yesterday, was redone and came out as an even larger den.
Now I know this can be useful, for roleplayers and use for more creativity, but I feel the most space we REALLY need for a den is about the size of the Mushroom den.