[Jarmsy]

Plenty of mathematics is ugly. Just look at optimal packing. People like to focus on the elegant parts.

[gus_massa]

A lot of the ugly part of math is hidden inside lemas and theorems, so the main part of the proof can be hopefully straightforward.

Anyway, I agree that people like to focus on the elegant parts. Math popularization materials have too much kawaii math.

[GuB-42]

A notorious "ugly" proof is that of the 4-color theorem.

It has been proven using a computer. The problem was first reduced to a few hundred cases, then a brute force algorithm was used to solve each case.