At our table, when we alter/remove races and classes for a specific world setting, we have a player that complains that everything isn't available, and doesn't like restrictions. I am not a fan of shoehorning something in just because a player wants to play it, and neither is the other DM at our table. For example, we've played in Dragonlance and there have been disputes over the restriction on spell schools/Tower of High Sorcery test at 3rd level, and what races are available (no Tieflings, Dragonborn or Halflings, but Kender and Minotaurs are playable.) This comes up as well when that player is the odd person out when it comes to alignment.
We've also leaned against certain characters being played because it would derail the adventure too badly (i.e. playing a Draconian in DL1, or dwarf wizards)
Do you ever have players complain about restrictions/changes based on theme?