Why doesn't anyone make an SLR lense with a large range of focal length?

Why doesn't anyone make an SLR lense with a large range of focal length? Like most people with SLRs own one lense from about 28mm to 90mm and another lense from 70mm to 300mm. Wouldn't it be nice to have one lense that goes from 28mm to 300mm? That's just a 10X zoom range. If companies can make camcorders with 40X optical zoom, how come there aren't any SLR lenses with the same range?