Okay, I'll add my 2 cents worth:

I am probably an 8 on your visualization scale (particularly my visual and auditive and tactile imagination ability is well developed, but I can't imagine smells at all), and I have at least one LD per week.

I have actually experimented with visualization during lucid dreaming, and my experiece is that imagination works exactly the same in dreaming as it does during waking reality. In other words, the visualized image appears on a separate "plane of existence" from the lucid dream, the same as it appears separate from waking reality. Consequently, I do not believe that imagination (or visualization ability) and lucid dreaming are closely related.