I can already imagine how ridiculous a player would look like stuck in a climbing animation while spinning around looking in different directions.
Although I can follow the logic in general, I have to say:
There are lots of things happening in this game that look/are/have at least the same degree of "strangeness" as this.
-fly/ride a vehicle fully submerged.
-dig away stuff underneath thingys, and they start to "float" because they're invisibly attached to other stuff sideways by a solid string of air.
-behaviour when you squeeze-clip yourself through half-blocks and/or some "fence blocks" (your head/pov is always inside the above material)
-"water" (place and remove blocks under water and see what happens)
...just to name a very few that somewhat line up with this supposedly "would look too weird if it were done" thingy.
Don't get me wrong, I don't care or complain that there should be a proper climbing animation.
I'm ok with the strangeness as is. And I wouldn't complain either if there was an animation that would look weird...cause it would line up quite well with all the dozens and hundreds of other "common" weird things in this game that you don't even recognize anymore after some time,
because they're part of "unfinished business" or mainly even unmanageable/given facts because of engine limitations.
Just sayin', the point "it would look weird if.." is not really a legit argument if you ask me.
Let's just say there are other priorities.