Free rolls are not something that someone can get rich on, but there is always a chance to win $200 or some other slightly bigger winnings than those initial 7 satoshis (more or less depending on the BTC price). For some, even that $1.44 per hour would be a very good salary, because in some countries people work a whole month for less than $10.

As you say, you collect a few more things in each free roll, and each 1 reward point can be exchanged for 1 satoshi when you collect 100 000 of them.