FFXI, Aion, RFOnline, Vanguard... there are a LOT of MMOs out there that have featured the pet as the medium for all (or most) of your skills rather than casting them yourself. It's been done before and that is how Summoners in the FF universe have ordinarily worked in the past. WoW's Warlock works because the mechanics make sense within the lore of WoW's universe. FFXIV's Summoner does feel very cobbled together with it's random combination of elemental pets and a bunch of poison spells. The fact it imitates WoW's Warlock so closely is sort of the problem for many I think.