The tight draw is the most limiting factor to an otherwise great tank. The more air that can go past a coil within reason, the more vapor you will get. It also helps keeping the coils from getting gunked up prematurely. I too believe it is the tiny holes in the atomizer itself. I don't like having to take long draws from a device, which is why I liked the XL cartos and such. I also found that restricted draw on such devices is what helps contribute to burnt hits.
It would be cool if they could make our hardware free flow and have an adjustable valve at the connector end to custom tailor the draw at the user preference. Say, like an air mixture needle valve that is found on a carburator on a gasoline engine.
ETA: On the VN I have, there is a tiny nipple (as in the circled photo above) on the atty head positive post that directs the air to the atomizer. I drilled mine out with the next size up drill bit to that hole with a pin vise. The nipple gets taken out in the process leaving just the main body of the connector. The air flow is better. I can see myself going up one more drill bit size to make the draw about perfect, but it is noticeably better with just one size up.