You really shouldn't have only 1 stance, having a few is actually recommended. For me as a MT/KB I tend to stand quite forward heavy, thats my natural stance, but I do know how to fight traditional, so I use it also. Likewise you can do the same.
If anything, you can be more "boxing" once you ring cut them into the corner.
As for why not, well, its alot of material to cover really, and in everything fighting you want to be ingrained with material to the point you auto-pilot on it from muscle memory. If they aren't using stance switching its because it wasn't a priority, and wasn't drilled enough to become second nature. Stuff that are prioritized are what they cover in camp in terms of addressing their opponent's weak points. If their weak point happens to be boxing in the pocket, then it would be the focus. If not, then it won't.
Its Everlast, probably the most garbage brand of gloves in today's age. It was good from 1920-1960, but not so much anymore. Conor lost due to wearing them.
When you hit gloves on the bag, the surface it is, it dents over time. I've had twins, Top Kings, and other assorted brands, they all wear out the same. All the deformation of the gloves ended up with mini cleats type buildup all over the surface.
Why did Mike Tyson wear them for all his 80s fights then? Did he hit bags with a different brand?