To be a little more explicit about why net neutrality is important in the long-term, it's to allow small companies to compete on the Internet. If Google or Facebook can pay for faster access than some new startup, they'll have an innate advantage over the startup. It increases the barrier to entry for companies on the Internet, all so ISPs can make a few extra bucks.
The situation is a bit like drug addiction. Obviously it's better for a person's health to not shoot heroin. But an addict will always find the immediate benefit of one more hit more compelling than the vague, long-term benefits of getting clean.
Telcos understand this dynamic, and they're trying to play up the short-term pleasure - by offering so-called "free data" - in order to distract people from the long-term harm and drum up support for suppressing net neutrality.