What most of the people saying "should have paid him a long time ago" are meaning, and even JJ said this on the Macafee show, is they should have signed him to his extension first thing in the off season.
There were several players at his position that were also up for extensions. Instead of negotiating earlier, and setting the market, they are caught with their dick in their hands and have to match the market now.
Setting the market would have netted a contract in the $35m/per year range. By waiting, you're looking at $40+. That's a huge difference, and signing Rodgers or not had no bearing on Watts contract. This wasn't a normal Steelers off season of playing restructure to create space, we still have $18m in space after the Rodgers contract...
JJ Watt said it out loud, the home town discount goes away when you wait this long.