considering the amount of discussion on this forum about the character of different M-mount lenses, I'm amazed no one has suggested that medium format lenses have different character than 35mm lenses.
For example, the lens light gathering area of an 80mm lens at 5.6 on medium format is much bigger than a 50mm lens at 5.6 on a 35mm camera. I'm not talking about film area here but the amount of lens area that sends light to any single point on the film. Medium format lens have bigger diamaeter for same size f-stop. That will make captured information much greater for same point in subject And its made bigger on the film. So I think its not just magnification from printing. (it's analagous to the quality of a pixel being higher for some cameras than others.) Or you could consider that telescopes use massive light gathering areas to get the quality they require. It's not just magnification as you could use a small light gathering area and magnify that but you don't get the same quality as the larger light gathering area.
Having said that, if you work at optimising your 35mm with the right film and developers you can get fantastic looking images so I don't think that just moving to MF is some kind of magic bullet, especially when you consider its size and heft etc. For example, I have frequently heard people say a Mamiya 7 is the equal of Large Format. Well if MF can be the equal of LF then small format can be the equal of MF. With small format, film and developer control is everything for ultimate quality.