I should probably mention that I'm in the United States and HB is no where near 'accepted' here as it is in other countries.
Yeah, I wouldn't say 'mainstream', but it seems in some areas it's considered 'trendy'. A lot of people assume we chose HB because it's the 'cool thing to do', which is ridiculous because we take a lot of flack for our decision and most days it in no way feels cool (my DH just received an email from a co-worker the other day that called me both 'outdated and naive' because this is the 21st century and we now have drugs and doctors to 'take care of that problem'). I could careless about doing whatever is 'cool' - we chose HB because it's natural and allows for a much gentler birth.
I had to laugh when we recently went home to visit family for the last time before the birth. We were explaining HB to our family members. My grandmother, who is 86 years old, said, "There's just so many newfangled births these days!" in response to our HB. I laughed and told her that giving birth at home is in no way new - in fact, it's probably one of the oldest methods in history : )
I think it depends on the area. For instance, here in Georgia the laws are gray area - it's not illegal to have a homebirth, but there are no legal CNM's licensed or certified to do homebirths. The state passed a law several years ago stating that no more midwives will be certified or licensed for the purpose of HB'ing, so that breed has died out. There are only 12 midwives in the state that HB and none of them are operating legally in full. So not only do we have to battle the stigma surrounding HB ('it's dangerous', etc.), we also have to finagle the system (very rarely will you find a medical professional of any sort that will support or provide back-up care) and pretty much have to lie to others. This doesn't make for a good pregnancy for the weak at heart when standing ground.
There has been an increase in HB, though. I think part of that in our area has to do with the economy. I get a lot of messages from people asking for a referral to my midwife and asking how cost compares to insurance, etc. In a declining economy when people may or may not have insurance coverage (or insurance that isn't that great), people are considering HB as an option.
Also, as you mentioned, the stigma is slowly being broken down regarding who might have a HB. My husband and I are considered rather Conservative - not hippies at all. But HB appealed to us for reasons outside of cultural or political reasons. We admittedly were afraid we wouldn't fit in within the community, but found that most people in our HB community aren't hippies. They're just people wanting a natural and gentle birth. We have since adopted many other 'crunchy' ideals (non-circ, non-vax, cloth diaper/EC, doing away with medication when possible, etc.). Our families and friends have come to call us either Crunchy Conservative or Conservative Hippies. Either way, it's fine with us and we are blessed the with support we've received from the community.
I do hope that women continue to educated themselves and become familiar with HB and consider it an option. I am due any day now (I'm 41w6d) so we have our birthing pool set up. We've been using it every night for relaxation exercises and just some last minute bonding time. We both said the other night that it's a shame so many couples miss out on this experience and would benefit from it. We are so excited about our birth instead of being filled with fear and dread as seems to be the case with mainstream births in hospitals.