When I read contemporary theories of sexual ethics, they all seem to boil down
But note there's no conflict being saying that "if it's consensual, it's ok" while also saying there can be more to sex than pleasure and a bit of temporary (maybe very, very temporary) bonding. After all, saying something is ok is saying it is permissible, it isn't positively wrong, it isn't to be condemned. And something can be permissible without being optimal; it may not be positively wrong but may fall well short of being particularly to be admired or sought after.
Woody Allen jested "Sex without love is an empty experience, but as empty experiences go, it's one of the best". And there's nothing wrong with a fleeting consensual sexual romp (assuming neither partner is committed elsewhere, or is underage, etc. etc.). Which is worth reiterating in the face of the crabbed puritanism of screwed-up moralists, religious or otherwise. And cheap music and cheap booze have their moments too, contrary to other kinds of puritans. But that's quite consistent with the thought that we can and should strive to do better than always going for cheap and cheerfully empty experiences (whether it's with wine, wo/men or song).
There's a kind of deep intimacy that can be bound up with sex -- but doesn't have to be -- that is immensely worth pursuing (and which hiking probably won't get you!). But, to repeat, it doesn't follow from that that sex without the intimacy has to be deemed not even permissible, not even ok.