MP only isn't "half a game".
Depending on the kind of MP we're talking about, generally it is to me. I always just find multiplayer far less impressive in terms of production values, and as a result, value proposition, despite differences in actual play time. You have a bunch of maps, unlockables, weapons etc, all of which you have in most SP campaigns and then some, and granted the modes and balancing takes huge effort, but I've always personally assigned more value to well done single player experiences, where pacing, higher production values, more complex map and stage designs, unique encounter design, AI, narrative, voice acting, animations, set pieces, more emotionally weighty and diverse missions, cut scenes and all the rest come in to play on top of everything else. The latter just strike me as more demanding of time, and more expensive and costly to get right, which is why I think more games are simply cutting it out.
I don't really care if even Battlefield and Call of Duty campaigns aren't the best in the world, they're still fun. I'd rather them just do a decent single player campaign and delay the game if need to be to get it right, than simply cut it out. The latter is a cop out imo, especially when the multiplayer experiences really do not differ all that much.