Gay guys aren't any more creative than straight guys simply because they are gay. There's more of them who gravitate towards fashion and designing clothes cause that is an effeminate realm.
Straight guys do their share of designing too - just think architecture, mechanical devices, websites etc
There are many kind of creativities.
If its a logical creativity,mans brain(one of the brain part. right or left? i dont remember) is much better.
If its a sensual creativity, womans brain is better.
If its a mixed style of both creativities, mixed type of brain is better,
So there are many gay who use both parts of brain.
But you dont need to be gay always to use both parts of brain.