Well a couple of off the wall thought occur.
1 If as they say the quickest way to kill your sex life is to get married.
and
2 If as they say many homosexuals are very promiscuous
then

By allowing them to marry..

1 We cut down the amount of STDs
2 We reduce the sales of KY Jelly by at least 50%

Sell your shares, and buy a wedding ring!
John ;-)