Honestly the big reason mobile radios are more reliable is that they're allowed to transmit at like 20x the power of devices in the ISM band. That's not a cost thing, it's just a regulatory issue steming from (some rather outdated) concerns about interference in the shared environment.
I mean, it's true that wifi is sort of a mess. Marketing of the standards has gotten way ahead of real world hardware capability (frankly MIMO as it stands is basically voodoo snakeoil that provides no consumer benefit whatsoever). But it's no less complicated than all the junk going on in LTE either. Everything's a mess.
Wifi continues to have the extraordinary advantages of being privately deployable, performant, pervasive, and standard (i.e. ethernet-framed, so everything Just Works the way everyone expects). It's not going anywhere.