Nexo Knights is one of LEGO's best themes out at the moment in terms of design!
Let's just look at a few of these "unattractive" sets, shall we?
This bland mush of plastic pieces replicates that of a crossbow, doing so extraordinarily well. Sure, it might use the same color scheme as all the other hero vehicles (although I personally like the the uniformity), but the actual design of the set is beautiful. The main function just makes it ever so much better, with the inclusion of a trigger that launches the spring-loaded projectiles, similar to that of a Nerf blaster.
And this lair that has no aesthetic merit is done beyond well. With countless amounts of features that would keep darn near any kid satisfied and a more than unique design, I'm shocked that anyone can say that Nexo Knights is nothing more than a bland, everyday LEGO theme with no redeeming qualities.