i think that it's really good for kids to spend some time away from the parents and learn to socialize on their own. my son started for a few days a week a few hours a day when he was 2 and then by four he wanted to go every day!
it really helped him to make friends, learn sharing, all those important lessons that little ones learn during that time. and as a mommy it's really nice to have that time to get stuff done around the house without worrying about turning on the tv for a while or what not. it's nice to think that they are constantly doing activities and are active at school.
maybe have your hubby visit the schools with you so he can see the other kids enjoying it and it mayb sway his opinion?!
good luck!