High magic also strips magic of its inheritent power and meaning, making it is as trivial and boring as boots your character wear. And that is something good fantasy world doesn't let happen. This is what Tolkien for one figured out immeaditly (magic is vague and minimalistic but utterly powerful. Ways it works are obscure as are the rules governing it. Compare that to FR where every commoner could theoretically carry magical trinkets)
Magic is rare and dangerous (DA):
OH MY GOD THAT GUY SET HIM ON FIRE GAAAAHHHH RUN
or:
OH ****, that guy is dangerous, rogue, try to sneak at him from behind and put some cold steel between his lungs while we distract him
Magic is trivialised (FR for example): crap, that guy shot fireball at us. Cleric, heal us! thnx. K guys lets drink these potions of valour, owl's splendor, cat's grace, bless, heal, barksin etc. and kick that guys butt. It's not like that fire did much damage anyway thanks to our 40 % fire resistance rings