Personally, I think if there was a birth control option for men that was even remotely in the same ballpark as the pill in terms of effectiveness, reversibility and pre-plannability it would easily equal or surpass the pill's usage rate.
1) Bag over the dick - makes sex less enjoyable
2) Fully trust your partner to not "forget" to take her birthcontrol or lie about being on it in the first place.
3) Abstinence.
I'm not suggesting all women or even a significant percentage of women are evil liars. However, there have been many studies & surveys that have indicated nearly half of all women are willing to lie about contraception in order to get pregnant, regardless of their partners wishes, and fully half have said that if they became pregnant by another man but wanted to stay with their partner, they would lie about the baby’s real father.
I'd much rather know for sure by taking personal ownership of birth control myself.
I don't know a single woman who has been happy on a single form of BC for a long time. My fiancee was on the implant until she started bleeding and didn't stop for five months.
Genital bleeding is really a very gender specific thing. Women already bleed from their genitals the issue is that it is now prolonged. If a man started bleeding from the penis that'd probably be a fairly serious condition lol. I get your point though. That said discomfort is a perfectly reasonable trade to avoid 18+ years of responsibility and a financial cost currently estimated at $250K per child (not including opportunity cost mind you)