It's a lazy way of constructing a conversation topic.
You are pointing out that it's a figure of speech, but then all your examples are metaphoric phrases, where as the one in question is just attenion seeking, and not well thought out.
'Am I the only one who thought the ending to was shit?' would be much better phrased as 'I saw the end of last night and was dissapointed' then using the OP as a way to say why and posing the 'what do you think' way of opening the discussion.
The other issue I have with it as a phrase is that I have never heard anyone say it.... Literally cannot think of a time where I have! Imagine you are standing in your favourite pub with friends, and out of the blue another mate pops over and opens with 'Am I the only one who thinks Stella is overpriced?' It's a terrible conversation starter, because as it was pointed out before, it is a closed question... it doesn't invite thought to the answers and only seeks clarification.
I don't expect people to use perfect english online, hell I know I don't, but I do expect a bit more thought gone into a conversation topic!