Not just to you, but your post gave me a post to ask it...
Is the DM who always has the same restriction when running D&D cutting out a lot less playing opportunity than the GM who only runs fantasy games and never does any other genres (supers, post-apoc, space opera, western, steam punk, urban fantasy, etc...)?
How is not having casters less internally consistent than this plethora of x,000 year old civilizations always being stuck in the late medieval/early renaissance and never having developed (possibly partially magical) steam engines, firearms, airships, printing presses, etc ... ?