99.9% of the time whatever game i buy i play to completion. i've heard the argument "i'll read a book if i want a great story", but that doesn't hold up for me. would that same person say something similar in regards to movies rather than videogames? i see it as a waste of time to not learn how storylines play out as opposed to abandoning ship for the same perceived reason - wasting time. it looks like those stats average to about half a game's length, so if you already invested that time why give up on something that could make the whole that much more enjoyable.
but maybe even more important than missing out on story is robbing yourself of increasingly challenging gameplay/more involved mechanics the further you progress. even with that said, i rarely replay games - especially more linear ones - once i finish them.
as you mention, i think the problem is too many options, and it's directly related to attention span. it's harder to thoroughly, singularly enjoy a game nowadays. you can't even put to much of that on the individual, there's just so many distractions. crazy to think games themselves can be distractions to games.
i don't think the structure of games is the problem, it's just the environment we're in. unavoidable. i mean even the 2 walking dead titles cited, those are the closest to movies/shows with less emphasis on gameplay, and they STILL aren't finished to completion. people always think they're missing something, slow the fuck down and just try to enjoy yourself.