For me it was because cheap cases are small and mean you can't put any decent hardware in them like radiators or fans or gpus so it's money wasted on a shit case
I have an appreciation for electronics in general and if I get something on the cheap that works well I'm proud to show it off, that and windowed cases start off at prices lower than most non-windowed cases.
Because one person's "ugly" is another's beautiful? Who are you to judge what is/isn't a good-looking motherboard? Just leave people be and stop being so judgemental.
Because maybe people spend their money how they please and don't care to cater to the opinions of some internet troll that would just find something else to bitch about regardless