You never know .... one day may be coercer will able charm none named mobs in raid instances (so far only 2 places I know where you could do that SC and LJ)
Major problem is that Master 1 tier 5/6 about as good as Adept 3 tier 7 (well Master 2 Magus >>>> Adept 1 Auspex) so the only spells that worth getting from tier 7 is masters or no upgrade at all for those who already have full set of t6 masters...
Genereally higher version of spell have less resistance and longer duration thus I would not getting Adept 3 of Domination while I have Master 1 Dominate but will definitly go after Master 2 Domination
What else it good for? - well aside of raiding (and yes that the only thing that left at lvl 70) you still have farming (and if you have [expletive haxx0red by Raijinn] load alts you oughta do it a lot)