I don't understand why it's so infeasible that improvements in cigarette technology could result in cigarettes that are worse for one's health because they've been more aggressively optimised for tar content as officially measured, or shelf life, or cost of manufacture.

As for the theory that modern smokers simply suck harder, I'm not sure that's so implausible. Light cigarettes are more common today, and most light cigarettes seem to get their lightness entirely from lengthier filters that have small holes in the paper. (If you use the tobacco for some other purpose, e.g., as filler for an unfiltered marijuana cigarette, then you'll find the smoke just as harsh and the roach paper no less tarry.) This requires a more forceful draw to avoid that unpleasant "sucking in air" sensation.

I've also noticed, on the occasions that I've checked recently, that cigarettes today tend to have lower advertised tar and nicotine content than the ones I smoked as a teenager. So perhaps that could result in a similar effect.