I don't know exactly what you mean by tower>kills, but really, you have to consider that a quick teamfight can mean the destruction of 2-3 towers within seconds. 4-5 champions (depending on how the teamfight ended) can take towers down at remarkable speeds.
Also, about the whole "don't tower dive until level 6 thing", as long as you know you're going to kill your target first (assuming it's a 1v1 dive), I believe it's well worth it. Even if you die too, as long as your target dies first, you'll both get the same amount of gold, BUT you'll get the experience, putting you at an advantage. This is just from my perspective though.