I'm a proponent of e-bikes. I do think they can get, and keep, more folks riding. Sure, I've seen plenty of folks in their 70's riding too, but not everyone gets to that age in good health. My dad (who live in the Netherlands) has had a lot of health problems, but his e-bike allows him to keep doing the longer rides and go on cycling vacations. E-bikes are immensely popular there (as are regular bikes, of course). I think it's one of multiple factors that keeps people there riding for so long, and it's fabulous.

With the hills around here, e-bikes would be nice for commuting too (not applicable to me now as I work from home). If it keeps more cars off the road, great! Especially during the most polluted months around here (esp. January and July).

Right now the price points aren't quite there yet to really grow this segment, but the increasing competition might get them there.