Flex cuts can be nice but a lot of PCBs nowadays have flex cuts because it's the cool thing to do.

The current meta is all about flex and bounce, so having soft plastic plates and a ton of flex cuts on the PCB is going to make the board jump up and down when you're typing on it. This can feel over the top and since all the energy is used up to move the PCB/plate assembly, the sound can be quite underwhelming. Lots of people nowadays don't understand that more of something isn't always better.

Instead of talking about the keyboard feel, people (reviewers and content creators especially) do a "flex test" where they push down on the keyboard with 5 kg of force and showcase how much the plate/PCB assembly bends. That doesn't really give you an idea of how it is to type on the keyboard, but designers and manufacturers accommodate their designs to these things because they think it matters.

There is nothing inherently wrong with flex cuts, but depending on the execution you can really see who's doing it for a nicer typing feel and who's doing it to sell more keyboards because it's the current hype thing.