Why aren't we satisfied with walking anymore?
Umm, it's slow? It's unpleasant. You have to dodge assholes who run red lights. It's not intense enough for a workout. It does not work your entire body.
Do you need more reasons?
I row 10,000 m five days a week on an indoor rower and I use mechanized transportation to and from work every day. The 10,000 m on the rower would just about cover my round trip *in a rowboat*. An equivalent amount of energy on a bicycle or walking would get me to work and back twice at least. I don't walk for the reasons I mentioned. I don't run because I don't like to show up to work sweaty and I have too many injuries from the knees down to do it for more than a week without crippling myself. I don't ride a bike because I live in LA and I LIKE LIVING!
If I didn't think some jackass in a car would try to nail me on a yike bike just because he didn't like the way I looked, I'd probably get one. Instead, I savor the thought of the thousands of pounds of metal around my body as I commute to and from work.
The antagonism towards segways and yike bikes even on the hyper liberal /. drives me away from these environmental alternatives because I know the attitude you and others show here is expressed as dangerous aggression on the road. I'd rather mother earth burn up in a stew of CO2 than make myself a target for drivers who are insecure about their own masculinity and aim their SUVs at everything that doesn't have four wheels.