Just because most teams don't, it doesn't mean some of us don't want them to.
There also isn't a single NCAA team that uses pink. Should someone not be allowed to have pink trim if they want, just because no real teams use it? The whole point of this thing is to make our own teams. If I want MY team to wear colored socks, why shouldn't it be possible? It's not a feature killing flaw, but it would be really nice to have it as an option.