I WAS a Wedding photographer and I can see the benefits of both.
For me, I already have a fine EF 70-200/2.8 LIS II that's well proven and paid of it's self over and over. It was never a main go to lens of mine, I far prefer the EF 135L. The RF version is a lot easier to store in a lens bag and it's a fair bit lighter. However, optically, there is no discernable diffrence in the end photos. Because I already have a EF mkII, the side grade to the RF version offers me a bit of lightness and ease of portablility. That's a little bit of benefit for a £2700 side grade! AS I've said before, the loss of teleconverter use realy reduces the verstatiliy of the RF version compared to the EF version. The whole point of the TC is that I don't have to take yet another lens with me. If you find that you need to take an addional 100-500L with you then it points to the fact that Canon have taken the TC option away and upsold you another (expensive) lens.