"[...] mounting stuff isn't always as simple as mount(8) [...]"
Most definitely, totally agree. But then, it's a problem to be fixed at the system level, and to try to provide a dektop-independent interface for desktop environments to hook-in -- instead of kludging it at the desktop level.
For one data point, I just finished "fixing" the Gnome metadata of one user: the emblems and comments disappeared just because this user's harddisk changed and the metadata are tucked away in some obscure database in the home directory... tied to the disk's UUID. Eek!
Look, I do understand that the desktop folks want to get things done, but this stacking up of leaky abstraction on top of leaky abstraction just scares me. I prefer to stay clear of that and to think of better alternatives -- if there are any. That's all.