Two reasons the 10MM never caught on. First, the gun it was originally intended for, the BrenTen, never really made it into production, for several reasons, mostly money. Second, the FBI almost adopted it after the infamous Miami Shootout, but because of recoil and a couple of other factors, adopted the 40 Short and Weak instead.
I like 10MM, but store bought ammo is expensive and hard to find, so that hurts it for personal defense. Dan Wesson makes a 1911 pattern 10MM that I'd like to have but it is expensive. Actually, 10MM is a lot like 41 Magnum, besides being very close in ballistics in many loadings, they both have very small but very dedicated followings.