This kind of thing pops up repeatedly. There's some big, splashy news about a male contraceptive, and then it flames out, or ends up being vaporware.
The problem is that you need to stop a few million sperm with every single ejaculation; reducing that number by 99% means that you're still risking pregnancy. Severing the ductus deferens (a vasectomy) means no sperm get through; trying to clip or block them means that some can potentially get through. Hormonal BC has the same issue; while it significantly reduces sperm count, it may not eliminate it entirely. (And there can be some really significant negative side effects from eliminating endogenous testosterone production, since hormonal levels need to be pretty far out of whack before there's a really big cut in sperm production.)
OTOH, women have to stop two eggs per month, or stop them from being implanted in the uterine wall. A 99% reduction in fertility for women means that it's very, very unlikely that they're going to be able to get pregnant.
(Yes, women suffer from hormonal BC as well, but some women need it just to be able to live normal lives. It's overall less of a problem than it ends up being for men. And women have the option of an IUD as well.)
Personally, I'm in favor of vasectomy; it's allowed me to avoid having any children for 20-odd years now.