All you got from all I have written is 'because it looks neat'?
I give up.
Other cultures eat in other ways, thats fine too, they have rules and constructs that suit where they live and how they live.
If you wipe your arse with your right hand, in a place where clean water is scarce and toilet paper non existant, then eating with your left hand only makes perfect sense.
Im sure if thats where you happen to be eating, and you whip out a knife and fork, no one would really care, but they might be curious, confused or think that you're making a point that you're better than them in some way perhaps. Start eating with only your right hand and they might well think you're revolting (or that you wipe your arse with the other hand, who can say).
Again as I have said before, I am not saying these are right or wrong, I am saying these are why these particular 'rules' exist here in the UK and that some of it is still sensible.
I have no issue with people eating with their cutlery the 'wrong' way round (where have I said I have?), but I do take issue with people eating in a way that negatively affects others (pinging food about, clattering loudly, chewing with mouth open, talking with mouth full, leaning across others, all grim stuff that generally leads me to think the person is thoughtless and inconsiderate).