Well, other than simply a repeat of Sturgeon's Law (90% of everything is crap), I'm not even sure that I agree with this. There have been so many really good reboots in the past ten or fifteen years - Battlestar Galactica (at least the first three seasons), Doctor Who, Batman, Spider Man, Transformers, and so on.
The problem isn't that it's a "cash grab" or "inferior". The problem is that people have a fixed idea of what that property was in the past, even when that idea only exists in their head, and then pretend than their taste is grounded in objective values like "canon". It's completely intellectually bankrupt. The only reason that reboots are "inferior" is when the person doing the complaining doesn't feel like their tastes are being catered to and their tastes are the only "true" vision of whatever the material is.
We saw this with Star Wars, the rebooted Star Trek Discovery and on and on and on. People figure that they know the "true heart" of something and anyone who disagrees just isn't really a fan. Good grief, that was the heart of much of the edition wars.
It just makes me so happy to see IP holders basically tell these gatekeepers to go pound salt and declare that canon is what the IP holders say it is.
Depends we've also seen multiple franchises crash and burn.
And others like Transformers rapidly become poster child's for diminishing returns.
There's a right way and a wrong way to do reboots it seems.