It's always been like this since 4.0. However @ lvl 80 the racials gave 80 resistance and MotW was less than that. The other resistance auras would overwrite the appropriate racial since they gave 130 resistance.
Racial resistance is indeed useless in raids.
It's somewhat useful in PvP I guess, although I would assume most caster have some spell pen to counter MotW/Kings nowadays.
But hey, atleast it works while solo'ing!!