Healers have to heal... It's not as simple as that. Sch have to dps and only support at some point by shielding /healing a bit. Reach the dps needed for midas is quite a thing, and even if your team is good, unless you go there with a great ilvl, you'll need the off healer dps. And selene's buff is quite important to this point.
( but i agree with you that eos got way better skills than Selene....)