AT&T tried this and it didn't go well. For a time you could get a discount on your internet if you opted into their data tracking programs. From what I heard, there was a lot of complaining and little uptake, which is backed up by the fact that they cancelled the program less than a year later and just started charging everyone the lower price (and claimed that they stopped the tracking).
I think people don't want to be reminded that they're being tracked, which is possibly why it went poorly, but this will be a problem with any company that wants to do opt in tracking.