Theres more to it than just a bug fix.

I would consider performance incerases and multi core calculations an advantage, especially when working with particles, fluids, cloth etc. Also mental ray rendering previously hardware rendered particles, as well as being faster a pretty big thing.

Again if you dont use them you wont find them earth shattering, but again no ones forcing you to upgrade. You chose to, if youve got it then you must have either shelled out the cash or downloaded it via the platinum membership, which if its the latter just uninstall it, if its the first then you would have known about plug-ins being disrupted.