I don't think a spouse will need their own DTV (possibly won't qualify). I think the carrot on the stick for the DTV is to make life easier for married couples. The Info provided by MFA states only marriage certificate
A lot of people are being very negative towards this new visa because it's a game-changer. It's the biggest upheaval in Thailand visa history. It's virtually an open door to anyone who wants five years in the country
That might depend on how much money they are prepared to throw around. Unfortunately the criteria for the DTV is hardly exacting, so it's going to encourage a lot of deadwood, people who are long term tourists who just want to do nothing and live on next to nothing