[chmod775]

"Why not?" here is an idiom for "I know it serves little purpose but I did it for the fun of tinkering with stuff."

[Dylan16807]

"Why not?" can mean a lot of different things. That's why it can be helpful to get an actual answer.

[PopeDotNinja]

I thing the "Why not?" is another way of saying that you've put more effort into understanding the motivation behind this project than OP did.

[Dylan16807]

That would be wasted effort, though. Sure, I can come up with a dozen potential reasons. But I want to know the actual reason(s).

[PopeDotNinja]

I can't tell if you're trolling. Sometimes I do stuff because "Why not?" sounded like a good idea, and I reckon others do, too. That's all I've got.