Well, after some thought on the subject:
I think that Medieval Europe rewrit for the presence of clerical and divine magic of a DnD scale and nature would actually result in a more magical environment than we see in most DnD campaigns.
I mean there are three versions of medieval Europe relevant to the DnD game: There is the literary version that consists of both contemporary and after the fact narratives, the twentieth century historical view of the middle ages, and the idea we have of how people in the middle ages more or less viewed their world.
Two of these versions, 1 & 3, are pretty heavy in elements of the fantastic. One is filled with wizards, paladins, exorcists, saints, and monsters. Lots of magical people. Three is less filled with
magical people, though they may be more potent. But three does have lots of magical features, dragons on the edge of the world, Prester John's kingdom, strange alchemy, faeries, dragons, shrines, demons, miracles, relics, ruins, towers, and the wilderness generally.
The second version denies much of the relevance of magic but still recognizes that it was around. Both in terms of three and in terms of many of the intellectual concerns of the period, particularly in alchemy, religion, and law.
Now DnD itself tends to be 1, 3, & then 2 in terms of priorities of magic to its own system. There do tend to be a lot of magical people around, often equal to or more than 1. But magical places are really rare and largely unknown or created by easily tampered with affects of magical people rather than the other way round. Even the magical radiation of Drow lands is largely gone. And DnD rarely tries to put together magical conceptions of the universe as complex as those that are recognized by the second version.
So if you merge the three version and the DnD version. You end up with lots of magical people, in a very magical landscape, with complicated ideas about how everything works, but a pretty flawed general conception of how it all works.
Even if you just go with three you end up with a good few magical people, only slightly less powered than default DnD, in a really magical world, a lot more powered than default DnD.