I think why people might like buckling springs as their introduction to quality keyboards stems mainly from two sources: nostalgia and hype. A lot of us, myself included, had fond memories of using Model Ms when we were younger, and purchased one out of nostalgia and liking the feel of buckling springs. This became the "gateway drug," causing us to search out other mechanical 'boards. For another group of users, listening/reading the all the hype on the web and living vicariously through others' nostalgia prompted them to buy an M.
I would imagine that if you removed those two phenomenon, that many users might find buckling springs too heavy, especially if they are aware of other alternatives. These days, since I have been using Alps and Cherrys, I find buckling springs heavy and fatiguing. A nice switch, to be sure, but not one that fits my everyday typing needs.