I totally agree with the #1 comment, it depends on each family. My mother didn't ask for a Baht either, besides, she doesn't need money from my husband to make her life better because it's already great :)
I understand why Farangs don't like this tradition. I don't really agree with it either if the family DOES NOT NEED the money from your marriage.
I've heard that some families spend that money just for BIGGER TV, BETTER radio or stuff like this that they've alread had them. But they want BIGGER AND BETTER ones, even though the ones that they have are already GOOD enough !
I think it's more important that you still take care of your mother by any way like giving little amount of money (not little like 10 baht:P) or buying something (even food) for her whenver you can. I also think that being a good human being is the best way to show your gratefulness :)
Um..... it's difficult for both sides to understand this ... Some Thai families do believe in this tradition, but at the same time most of Farang disagree with it ! Hopefully, you can make your (future) husband understand this enough to make him willing to follow the tradition, otherwise it might be a problem for everybody. - See more at: http://www.atriumtech.com/cgi-bin/hilightcgi?Home=/home/InterWeb2000&File=/home2/searchdata/Forums2/http/www.pantip.com/cafe/klaibann/topic/H4804423/H4804423.html#sthash.t44j6wUe.dpuf