Yeah, actually Kaer Mortem is well done and introduces the visuals pretty well, but, imo, it is a little too short and when you come to White Orchard there the lightning and the area is really too bland with that almost full blue sky with little clouds (as I see it, it would have been better that the two were inverted actually, since Kaer Mortem can practically be skipped almost altogether if you don't' care about the tutorial and the major part there is an inside cutscene). IMO it would have been much better there to have a 80%-90% strength as far as visuals go, to then subside in Novigrad (that has better and more diversified zones, more ample map etc, so the strength of the lightning/visuals can be compensated by other things) and then reintroduce full strength later.
I personally think that White Orchard is the blandest zone of all (apart some interesting areas) and that's the starting zone. Granted you stay there not very much, but the introduction to visuals there for users is really low. Novigrad is arguably even worse as far as lightning but the greater variance of locals, the ampler map, the vast cities and their population etc. make global lightning much less important (you can easily compensate with well placed atmosphere local lighting). At the very limit, since that area is so vast, you could create particular very well done lightning zones inside it (along bland ones) to keep the interest going.
Naturally this is all theoretical as you would have to test the outcome inside the game, but as a general rule White Orchard is completely bland in practically 90% of the map and that area is where the first iconic encounter of the game takes place.