Not only cashpoints
Well, yes, Norwegian does not give much of a cashpoint reward on an intra-European flight for 30 Euro, but when you fly on some of their long-distance route, and the better in Premium, the cashpoint balance is more noticeable. Moreover with frequent flights, you gain other benefits for flying, like free seat reservation, free bag, which again is a good value on EU-US routes. I also sometimes book hotels with Rocketmiles (*) and there I get so much for booking a hotel that I get cashpoints for several low-fare tickets. To me, the program is quite good. I like the fact that I can spend whatever Cashpoint balance I have on a new ticket -- not to wait until I accumulate 50.000 miles to be able actually spend them (like in my other FF programs). Any reward program is just a way to attract you to the same company. The main objective should of course be flying to and from places you need!
(*) Beware, sometimes Rocketmiles charge much more than other booking sites.