Motorcycle helmets actually offer good protection, while bicycle helmets don't. For any impact over about 10 mph, they are not going to signifcantly reduce the peak accelerations your brain experiences (it's your brain sloshing that does the damage).
Ugh. No. Complete nonsense. See the studies cited here: http://www.cyclehelmets.org/1139.html regarding impacts. Quality helmets that are fully intact offer awesome protection against impacts; both from the perspective of brain deceleration and pure blunt trauma prevention. The biggest mistakes that people make is that they look at a bicycle helmet, don't see any crushed polystyrene, and assume that it is safe to wear the helmet. Instead, the polystyrene is about 10 years old, is starting to lose structural integrity, and has had a few bumps that have further weakened it.
The other problem I see with most epidemiological studies is that they mix a lot of different factors (population growth, vastly different riders, changing usage patterns of bicyclists, etc.) and assume that the only thing that changed was whether people wore helmets or not.
Wearing a helmet is applying a different standard to risk than we do in many other situations. Cycling is actually slightly safer per mile than walking, yet we don't make peds wear helmets.
You're making the same exact mistake a lot of the researchers made: you assume that all cyclists behave the same and are exposed to the same risks. Basic cycling, on empty roads and at low speeds with regular pedals, is very safe. High-speed biking on twisty mountain roads with feet securely attached to the bike is significantly more dangerous. The vast majority of cyclists are of the former variety, and will drown out any impacts on people who engage in the more risky version of biking.
So why are cyclists singled out to wear the safety yarmulkes?
Because people are stupid, and most have trouble with the concept of "this type of biking is safe without a helmet, that type of biking is not." As a result, people just said "screw it, everyone has to wear a helmet."
As an additional point, helment laws are actually terrible for cycling safety. After Australia made helmets mandatory, cycling went down 1/3 overnight.
Familiarity an also breed contempt. You're inferring conclusions your data does not support. Furthermore, if people are so concerned about looks that they'd rather drive than bike because they think they look stupid in a helmet.... well, that's a problem with people, not helmets.
Finally, my head survived a fairly significant impact with the ground with no injuries (the rest of the body, not so much), thanks to the rapid compression and fracture of the helmet. I know helmets save lives. Do you?