Except it doesn't, those telecom companies are all able to sponsor cars/drivers/teams in any of the other NASCAR sanctioned series if they so choose. They chose to leave the sport entirely, which says a lot about their interest in the sport and it's fans. Sprint is paying more than any other company, so I don't see a problem with it.
Gone are the days of companies sponsoring 36 races a year and begging to give their money away. They all want value and exposure and I would say that it's a good deal for both parties. The teams are having to work a little harder to find sponsorship these days, but the HMS,JGR,Penske etc are still doing quite well. Now some are struggling no doubt, see Roush, but I don't think letting some telecom companies into Cup would change a thing.