Well, I can't answer for all "birth activists" but personally, I want women to be educated about birth choices. I want them to know that home is just as safe as hospital, and with much less risk of intervention. I want them to give birth in the place where they feel safest, and to know what is necessary and not necessary as part of labour and birth. (ie - induction because your OB is going on vacation is NOT necessary!)
If the research showed that the hospital was the best place, or that the birth centre was, or whatever, I'd be all for it, I think. But since research currently supports healthy women giving birth with minimal intervention, which is most likely to happen at home, I support and encourage home births.

Wow Rory - 8cm by the time you got to the hospital! That must have been quite the car ride! For me, it was more about the going home - I left the hospital about 7 hours after birth with DD2, and thought this is a pain in the butt! Had to pack everything all up again, get that poor tiny bean into a car seat, and drive home with her in the back where I couldn't see her, then take her back a day later for testing... With midwifery care here in Ontario, the midwife visits you at home as often as you need it for the first two weeks, and all your testing etc, is done at home too. Then at 4 or 6 weeks you go for your first office appointment. Much easier to manage!