I had to read this because I am generally opposed to removing features that I find useless because others may indeed use them...

That said, I forgot about the content room as it is that pointless to me.  I wouldn't miss it if it were gone, but let's see if anyone chimes in in defense of keeping it.

Genitals on/off...   I don't think this should go, but rather I wish there were a better way to replace any body part and create switchable geometries using arbitrary meshes that align and contain similar edges.  I'd love to be able to replace forearms with ones that have gloves/cuffs, closed zippers with open zippers, heads etc.  But genitalia are a sensitive area (ahem) for many.  I find the barbie/ken look disturbing, but if I wanted to walk a client through figure creation or posing, I'd definitely want figures to load with genitalia disabled.  If anything, there should be a way to mark any prop or conforming item to disappear with a global toggle.  Modern figures often have separate genitalia which renders the current toggle useless.

Dots aren't bad, what is bad is having to remember which dot holds what.  I think they would be more useful if mousing over them would cause a small thumbnail to appear next to the dots to show what is stored there.  That may have been a waste of resources long ago, but I think we all have the ram and diskspace to hold 27 thumbnails.  Maybe it could be turned off in prefs.

Figure height has the same problem as drop to floor.  It should be rewritten (based on the figures it was originally implemented around) to use the figure's body scaling.  How hard would it be to scale any figure to a certain height, or make sure any figure is actually resting on the ground (and offset it if wearing shoes)?  Along these lines, % of figure size in the object import seems totally obtuse and useless to me.

I still like the KK interface.  If anything, I'd like borders or snapping to allow me to easily move them as close together as possible without overlapping.  Maybe the camera control should be floating so it could be moved over the preview window?  If it were scrapped, I'd prefer something like Truespace's nav widget, or the option to choose cam controls which mimic other programs like Wings (Maya, nendo etc.).

Old content (lights/mats) should probably be removed or at least categorized to indicate they are for the P4 render or whatever.  I have long felt that the older figures should be replaced by modern equivalents.  I know many users have improved older figures by tweaking the joint fall-offs, adding weightmapping, running EZskin etc.  I'm not saying total overhaul, just that these figures generally look a lot better after just a little effort, and so should be updated as included.  New users would likely not know how to do this and so may not see the value of the P3-6 figures, but many of us still use them to create populated scenes or put people in the background.