To put it simply, yes.
Rock type Pokemon (not Steel and Ground) have their Special Defence raised in a sandstorm by 50%. No move types are naturally boosted by sandstorm, however moves like SolarBeam and Moonlight are effected in various ways. Of course, Sand Force still boosts the power of Rock/Steel/Ground moves.
To answer the sub-question, a Pokemon's behavior, appearance or capabilitys may be what granted the Pokemon the ability. Otherwise, that is simply how Game Freak wanted it.