There are so many advantages to riding -- gas money (I save about $5 every day that I ride to work vs. driving), cheap registration ($20 for 2 years in WI vs. ~$100 per year for cars), cheap insurance (if you're not 20-something with a sportsbike that is), easy to maintain yourself, easy to find parking, you get to enjoy the weather, it's more fun than driving, etc. etc.
Then again like you point out a lot of riders don't look at the details. You have to frickin wear gear. I've had people tell me "I spent all my money on my bike, I can't afford a helmet and jacket!" Well maybe you can't afford to ride then dude. You have to adjust your habits compared to driving. Maybe you can get away with a couple beers before you drive home, but you probably shouldn't when you're riding! You can't just hop on a 170hp bike and be safe; it takes a lot more training/experience to be a proficient rider compared to driving!
Motorcycling is an awesome and rewarding hobby, and it's practical in a lot of ways (at least that's what I tell my wife). But there are people that obviously don't think things through before they ride, and unfortunately that is pretty dangerous.