People about cosplay...
You absolutely do not have to make your own costume to cosplay! Made or bought, cosplay is cosplay. Cosplay is more than making an outfit. It can include makeup, wig styling, and prop making too, besides sewing the costume. Some people, like me, style their own wigs and do their own makeup, but can’t sew or craft. Some people simply wear the costume and don’t make any of it, and that’s fine too. This cosplay elitism needs to stop, of course it isn’t wrong to buy a costume. As long as you’re having fun, you’re doing it right.
It depends on what you mean by popular. It’s more or less exclusive to conventions, which have the benefit of only happening once each year per con. Attendees like myself have time to craft and sew awesome things. I know why I like it-it pushes my creative boundaries and has become my full time hobby and side-job. It’s very fun to be someone else, but it’s also fun to show off your work. I made my husband a great Groot costume for DragonCon last year and it was one of the best weekends ever. We had a blast as ‘Rockette’ and Groot. There’s something about participating in a huge fandom that is just pure fun.
I don’t think it’s really all that popular with the general public, when people don’t know who you are it can be disappointing. They don’t really know what to make of you when you come into a restaurant painted blue with a handful of storm troopers after an event or convention. Kids seem to go nuts over it though, I’m also a member of Rebel Legion and dress as Princess Leia for events. Adults are amused but kids go crazy for Darth Vader. Popularity really only seems to stretch as far as known characters.
Coming from a movie production background, you put on the parts of your costume that would interfere with makeup – possibly rubbing on your face when donning the apparel – before you put on makeup. None of the rest of your costume should be worn until it is just before “showtime”.
And costumers (both hobbyists and professionals) should be planning for makeup application and making a costume that can be put on without having to go over the head like a T-shirt does. Aside from the fact that this is easy to make, there really isn’t a good excuse for designing a costume that ruins makeup, or alternately, has to be worn while makeup is being applied.