A neat roleplaying bit would be to increase social standing for creative uses of transmutation spells. Applying social opprobrium for using the class' core feature isn't flavor -- it's punishment.
Well, I have quibbles about making things fun (punishing classes for using their features with in game repercussions), but if you don't like playing a game with him and become so angry about it that you rant and tear him down (which he didn't do to you) online where he can see it and to total strangers, then you're now jeopardizing that friendship for stupid reasons. Cut bait, explain your reasons, because your current path with end up with a bad game and no friend.
I am not seeing a lot of "tearing down", could you explain where that happened? I see a DM who thought his player was ok with how the game was going, and then was told to look at this, and found out that his player was actually really unhappy, and tried getting help from the internet to change the DM's mind. Centurion's reaction seems completely reasonable to me.
@Centurion! For what it's worth, I agree with you that restrictions and reactions make a world more interesting, but as you mention, not everyone will go for that sort of thing. I have one player who specifically builds setting agnostic characters to drag and drop to different games, and feels that limiting character options at all is a bad thing to do. I am personally quite proud of my current world, with its limitations and changes, because it is mine. I encourage you to continue as you are, and not compromise the basic ideals of your world to make someone happy.
For any who read that in a negative light, allow me to attach a disclaimer. I am happy to help my players build the character they want to play within my world, and help them tell the story they want to tell. That said, I am not willing to compromise the basic idea of my world because one of my players is feeling entitled (not directed at anyone, just a hypothetical fake player that wants me to change my world). For a simple example, would anyone want to play in a serious* low magic Lord of the rings game, where one player insists on playing a Jedi? Not a wizard who calls himself a Jedi, but they actually require a space Paladin with a laser sword.
*serious here means Not a beer and pretzels game, but an actual attempt to role play characters as they would exist in Tolkien's universe.