It depends what you're trying to be immersed in. Fantastical armours do a better job of immersion into a fantastical setting, and characterise both the world and the main cast. Realistic armours would look inappropriate in a game like Final Fantasy 12 or Morrowind and would break immersion.

KCD and M&B are explicitly trying to be realistic settings so of course realistic armour works for them.
Dark Souls does have fantastical designs like Kirk's armour, Ornstein/Smough, the onion knights, etc. but it uses them sparingly because the theme of the game is that all the fantastical gods and heroes are dead or corrupted and most of what's left is regular chucklefuck undead exploring the ruins.
Dragon's Dogma is a more fantastical setting but the game is an unfinished piece of shit and an inconsistent tone is only one of its many issues.