For AT&T to place data caps on any plans tells me they either really suck at managing their network, or they are greedy FN bastards. No home internet service should have a cap. Sure, you can go with the 1000 plan for $20 more (an idiot wouldn't since 1 TB is the limit on lower plans). But this practice won't stop for them and I'm willing to bet they will place one on the 1000 plan or greatly increase the pricing on it at a later date. Remember what they did on cell service. Additionally, other internet providers may catch on to this practice.
AT&T can keep their "free 4K" and stick it where the sun doesn't shine. They are betting with it, fools who buy the lower tier plans will quickly go over and they will make up their cost in the first month.
For those who say they don't know what they use in a month - check the advanced settings of your router. it may show traffic usage like mine does. Based on current stats, I'm about 200MB over 1 TB / month currently and don't feel I'm a heavy user.
Edited to add: Then the question is "how do they measure data"? is it down, or down/up. If down/up - which wouldn't surprise me, then whoa!