They're still clearly important, though. That's why B1G went after the LA market and will likely eventually come after some major markets in the south (Miami, Atlanta, Charlotte, etc.). Keep in mind, having all the streaming services and sports channels is a luxury that many people still can't afford, so games are still shown on a regional/conference scale on CBS, Fox, ABC, etc. That's where it matters.
Also, large alumni bases can be found in large metropolitan areas (a lot of Miami fans in NYC, DC, etc; a lot of SEC and ACC alumni in cities like Charlotte and Raleigh), so that also makes a difference.