What is the reason behind the Triumph 400's relatively immediate success.

I'm Not bashing the bike but it's visually clear that it's a run-out success. I see speeds, T4s and 400x's everywhere. It's clientelt consists of equal number of informed riders and squids. Saying this by experience I can see that most of these owner's riding sense is not that good. Many without helmets, some without mirrors , and many doing zigzag or riding mindlessly.