If we have to put up with each other, I see no reason why the rest of them shouldn't have to as well
See, I'm questioning the whole idea of "convincing." Not logically more convincing, surely. MAybe "satisfying" is a better word.
And I don't think you'll get as far with evolutionary arguments when trying to explain beauty as you would get with trying to explain morality, for example. If it's just sexual selection and survival, lots of ugly things would work just as well as pretty things. And lots of pretty things (sunsets, canyons, mountains, etc.) have nothing to do reproduction. Some, like the ocean or mountains, might even lure one to his/her doom. (One could make a similar observation for lots of the people we find sexually attractive - they might be very dangerous, which is part of the attraction)