Same reason that things were more all-time meaningful in all fields of life back in your childhood? 

More seriously, the 80s/90s/00s cable TV era demanded more content, enabled the “celebrity” as an autonomous force, blew up revenues and salaries through broadcast rights and endorsements. So it’s not surprising a lot of sports heromaking came out of this period (remember baseball/football star Bo Jackson?)

The period started with the NFL consolidating its takeover from baseball as “America’s game” and the NBA solidifying itself as a major sport, ending it with making its own challenge to football. It saw NCAA professionalization - modern football conferences and TV rights, the Bowl Championship Series, March Madness getting big. It saw the development of MMA (amidst the retreat of boxing), the rise of televised poker, the national consolidation of professional wrestling. It saw the decline of hockey along with its Rust Belt heartland, the expansion of the other leagues into new sunbelt markets, and NASCAR representing the emergence of a new Southern middle class into something like a national default identity.

Meanwhile, Europe could tell you all about the simultaneous rise of corporate big money celebrity football. A lot was going on.