I'll be hated for this opinion but... I think that those lenses are the most unnecessary lenses of the whole RF lineup. If Canon didn't do some kind of magic then the RF lenses are gonna be pretty much same size as the EF lenses with the adapters on them.
And considering the price of them if I buy one adapter for each of them then it would be hassle free with no significant extra costs.
Not hated, but you are obviously not the intended market for these lenses. I feel the same way about all the wide angle RF options that have been mentioned / requested because of my wildlife orientation. You could also use the adaptor argument for EF lenses in all categories. The reality is that Canon will need a full line of RF lenses to round out the R system. They can't launch a camera like the R1 without a fully baked lens lineup that will match the body / use case. I am a hobbyist, so I can accept the argument of using one of the EF Big Whites with an adaptor. If I was a pro on assignment, I wold not want to have an adaptor as a point of failure especially if I also needed a TC in the mix. Same goes when on a trip to Africa where an adaptor is just one more point of entry for dust. Canon is taking the same approach with the Big Whites they did with the RF trinity, get the best glass possible ready to support your bodies before launch (remember when everyone thought Canon was nuts before launch of R5/R6). Someone else pointed out there are competitive issues involved having RF BW lenses to complete with other mirrorless offerings. If I am buying a new R body and need a telephoto solution, whey would I want to drop $10k - $12 on a lens I KNEW was not the future direction of the system?
As a hobbyist, I would personally stick with an EF Big White I already owned unless the RF is significantly better/ faster/smaller/lighter. I sold my 200-400 f4 (which I loved) because I was tired of dragging around an 8lb lens. I would buy back in a heartbeat if they delivered a 200-400/500 f4 @ 5 1/2 to 6lbs. I am really hoping that Canon will commit to high quality DO lenses to solve some of the size/weight issues - like the EF 400 DO IS II.
BTW - I was going to take the adaptor approach with all of my EF lenses. After trying the R5, I knew I was never going back, sold everything EF and committed 100% to the RF system. The sale of the 200-400 (which I loved) was more related to size/weight and I decided I could work with the RF 100-500. No regrets on the conversion, but I do want another high quality BW quality zoom. I would love a RF 200-500 f4-f5.6 L IS @ the 5-6 lbs which should be possible considering the EF version III weight reductions.