As someone who as done mono and stereo recording and mixing, I can tell you this: Any stereo recording that is properly in phase will result in a noticeable boost in the center channel (+3dB) when folded down to mono. This is a fact.
The bass and piano are in the center on most of those RVG mixes. Drums and horns are usually off to the sides. Most of those recordings are in phase also, to RVG's credit. This means more bass and piano in mono.
As someone with ears that work, I can also tell you that the piano is often buried in those RVG stereo mixes. Regardless of his intentions, most of those records have a better balance in mono.
You are entitled to your opinions of RVG stereo recordings, and I am entitled to mine.
I've never heard any of your records, so I can only hope that you did a better job of mixing the piano on your records than RVG did on his.