The bigger issue is not the flag. The core is that this "feature" is not even used by its advocates - exposing unwritten, stale data.
The only justification for the feature or the flag is to take advantage of the side effect which makes ext4 go faster.
Note that on the ext4 list we did debate multiple techniques to fix the actual performance problem at the core here (whether or not random, single fs block writes to a preallocated file are a critical use case).
The problem with the flag itself is that people will use google, etc to search for "ext4 is slow" and suddenly come across the maintainer talking about how to make it faster by using this feature without proper context. Even the name of the flag is misleading - "no hide" sounds like we are doing something fishy.
Better to use a name like "show me other peoples data to make my workload go faster" :)