In my books Blizzard were never good writers. WC3 was decent, Brood War had a great Zerg campaign, anything other than that was always cheesy as hell and full of plot holes and retcons. I don't play WoW anymore but from what I heard they kinda took a dump on the lore since Wrath (which had its own story problems, especially the nonsensical ending to ICC).
Anyway, as to RTS, I think MOBAs have overstepped the genre in many ways. As competitive gaming (which RTS is played even close to competitively by a decent enough number of people, save the special snowflake SC2?) but also as casual gaming. For a lot of people, MOBAs are like RTS, except with only 1 unit to control and teamates on which you can blame everything. So it's much less stressfull than SC2, which is extremely demanding to play even at a midly competitive level.
I personally still enjoy Company of Heroes (1 and 2) and boot up Sins of a Solar Empire occasionally, along with an occasional Total War game (that I never finish). But apart from SC2, the genre is very much niche now.