I previously was one of the biggest advocates for bracket shuffling, but I have to say it has instilled a more defensive (and somewhat bland) mentality when it comes to teambuilding. Analysing your next opponent's teambuilding trends definitely affords you a lot more creative license to adapt teams and use movesets that might be weak in the general meta, but are designed specifically for the match up that you are expecting, and I do believe that is a great skill to have in competitive play.
Speaking as an NU player, I feel like the shuffle system has only exacerbated the already very match-up dependent nature of the tier; and does not leave much room for more niche teambuilds and movesets which, for me, are two of NU's most appealing properties. The process of innovation, and deviation from standard movesets, has become a lot more risky because it's now much more difficult to assess when it is an appropriate time to employ your new ideas. As a result, you end up seeing very similar team archetypes in most matches which I can understand may be boring for both players and spectators.
However, I quite enjoy having the ability to rigorously test and scrutinise a new teambuild in a tournament setting - where the competition is often markedly higher than in matchmaking - without fear of being counter-teamed. It can't be denied that a certain level of skill is required to win several tournament rounds with the same team, against all different types of matchups, both favourable and unfavourable. But, whether this system fosters a similar level of skill to the previous system is a matter of debate. I agree with points from both sides and can also see cons in both.
As Poufilou said above me, a lot of the arguments back and forth (much like my one here) have largely been founded on personal preference and rhetoric rather than objective evidence. Having said this, I don't see a way of objectively proving whether one system is "better" than the other, because ultimately "better" in this instance is an inherently subjective measure.
I don't think there will be an outcome that will truly please both parties, but it's clear that a lot of people are quite upset with the way things are at the moment. Maybe it's worth taking the democratic route and creating a poll where competitive players can vote on their preferred system, and going with the majority... But I'm not sure how you would define the target audience and conduct it in a way that prevents falsification. Difficult situation.