My one rule in life is that if something makes you feel happy and it doesn't cause harm to yourself or anyone else then do it, you don't need approval from anyone. So if you want to keep your toenails permanently painted, you go for it. Being playful and breaking conventions is the spice of life, without it you would become old very quickly.
See, I always thought Paprika was the spice of life...learn something new every day...
Yours, however, is an excellent point - no reason not to keep the toenails painted; if other folks don't like it, then F the F-ing F-ers!