I'm a bit out of touch with FLL (my kids aged out), but its not surprising. Little of winning a FLL competition is related to the robotic performance. The team that wins the robotic portions won't necessarily do well overall.

Given that, and the sophistication of many of the teams, and the way the competitions are designed. The best teams are usually just doing some form of preprogrammed dead reckoning sequence and getting a bit lucky and rigorously placing the bot at the beginning.

AKA, while the NXT/EV3/etc devices are capable of sensor feedback, few teams made use of it. Its likely all the FLL teams need for most of the competition is three motor forward/reverse.

PS: Maybe I sorta failed to respond to the main point, which is that the spike kits aren't there to be "cool" sitting on the shelf and excite kids who get them under the tree. They are mostly purchased by educational/FLL teams where the build instructions and/or goals are provided by a 3rd party.

Yes, Spike is brick, not Technic. It's for robotic cars, not machinery.

It's more geared towards organized lessons or competitions. In something like FLL, kids are given problems to solve on a board (move this from here to there, trigger this mechanism, etc) and they need to use the robot to solve it. So they are not building bipedal robots but tools geared toward a specific "mission" (an FLL term). When my kid did it the team needed to do everything, including building the robot, and needed to collaborate since generally each member of the team had a mission and the robot needed to do all of them in a certain time. This often meant returning home, swapping out an attachment and starting again, so a design that was quickly modified on the board was an advantage.

It's all arguably less fun, but certainly easier to sell to institutions designing curriculum.

EDIT: One thing I want to add is that though I also played with technic, I saw FLL attract kids who wouldn't otherwise be attracted to STEM because FLL had a social aspect. I felt it was a great way of introducing kids to robotics and programming because they could do it with friends and work towards some goal. I loved technic, but it was a solo pursuit and though that worked for me, it doesn't work for everyone. So when I say Spike is "less fun", I mean that it probably doesn't attract the kid who wants to build a robot, but it certainly did work in bringing in kids who would never play with technic at all.