I, er... posted a reply to UAPs comment a few days ago... I can't remember exactly what it was...
The thing is, the house common-rooms are only there because it's fun to have them.
They could just as easily have been called:
Giraffe House
Dog House (ha ha)
Rat Room
Tiger House
So what influences peoples decisions in going into the house? The titles, partly.
If you named one house "Pink House" the number of males joining probably would drop, however fractionally.
The second influence is obviously, as you've pointed out, the people.
But: If everybody in the world jumped off a cliff, would you jump off the cliff with them, or die of lonliness in a year?
Personally I think we're over-dramatising it.
It's just a one in four choice. Just depends on your personality and whether you'll feel better about yourself if you pick a popular house or try to make an unpopular house better.