Today in BJJ we brought out the crash mat, and practiced throws all class. In a year of attending classes at my gym, this was the first time we've done this. We occasionally do takedown based drills, shooting for a double or whatever, but not completeing it. Sometimes we do throws. Any practice standing comprises maybe 5% of total practice time, the rest being on the ground.
Its a problem, and its why I've been very interested in other arts, and am going to start Sambo soon. I have terrible takedowns, with my sloppy double leg being the only one that's remotely useful. I'd like my martial arts training to have at least a bit of use for self defense (although this is not why I train), and takedowns are required for this.
I think they're not taught because the ground component is easier to learn. I say this because for any throws to be done you first must spend a lot of time learning breakfalls. Throws themselves are difficult to learn, and its easier to get hurt practicing them. You can learn an armbar in your first class of BJJ; it will suck terribly, but I think a newbie would find it easier than learning a throw in the first judo class they took.
I do find it ridiculous how such an effective ground grappling art is so ineffective at getting things to the ground in the first place, but BJJ is super specialized and thats part of why its so effective.