I think it's interesting that DMs have such strong views about the player options that should or should not be allowed in their game.
I couldn't help poking fun a bit by turning the tables on you. Sorry, but it was just sitting there…
No problem.
Using your analogy, I think it's OK for the player to come and ask if they can play center or forward or guard, or if they can introduce some set plays into your run and gun offense. What's the harm? It's not like we're playing competitive D&D for a national championship or anything, right? It's pickup at best and a few variations can be tolerated.
Sure. That's within the parameters. That's like saying they want to be the wizard, or even (in the games I run and play in) asking if you can include a custom spell or feat that you designed yourself. I'm completely willing to entertain those ideas.
I don't really disagree with the various pro-DM comments. The DM is creating a story for the players and many get a lot of satisfaction out of crafting that story carefully. That effort should be respected. I just want balance where the player's efforts to craft a character are also respected. Using the improv approach, I think it's admirable for both the DM and the player to work together to weave the story.
One of the things that D&D has different is that it's an activity for fun with friends, not something you're getting paid to do or doing with a bunch of strangers. If you're doing it for your own enjoyment too, and your friends care about your enjoyment, you should be able to change the parameters.
Plus, I think the people who play Quiddich or a pick-up game of basketball and everyone who starts their own business or freelances would probably disagree with the assertion that either sports or employment can't have their parameters changed.
The issue can come in regarding what sort of work the DM has put into it. Take my current example. We're just finishing up the LMoP adventure. I made a small list of house rules (most of which never even came up), and told players they could play anything in the PHB (except I disallowed the Healer feat, because it rubs me the wrong way). I also told them this would likely be the last campaign I ran where that was the case, so take advantage of it now. Consequently, we have a dragonborn and a tiefling in the party.
The point is that I didn't put anything into that adventure or world. It is a published adventure that is in what for me is an alternate version of the Forgotten Realms that will never come to be in my normal D&D multiverse.
On the other hand, a lot of DMs (including me) create our own worlds and spend dozens or hundred of unpaid hours crafting cultures, pantheons, nations, histories, calendars, etc. If someone comes to that game and asks if they can play a race that isn't a part of my world, it would be like asking if you can play a Vulcan or Klingon in a game set in Middle-Earth. No, you can't. Maybe you can be an aloof elf, or a strangely honorable orc, but that's as close as you can get without taking a crap on the world's integrity. If you allow a Vulcan or Klingon you are no longer playing in Middle-Earth. It might work if you are playing some sort of multi-dimensional game where you hop around from fictional realities to other fictional realities all posited to exist in the same multiversal arrangement or something. But that is hardly a shift in your campaign idea that a player who has put little work on designing it has any right to even seriously
ask you to do, much less expect it to happen.
Now, if player asks, "can I be a member of an order of knighthood that is kind of like..." I can accommodate that, and am usually happy to do so. Unless the world is built around a few specific orders of knighthood being the only ones on the block, it doesn't mess with anything. It's like saying you want to be from a seaside village. I'd ask the player what they want the village to be like in general terms, or maybe even let them design it! But if they say, I want to play a cleric of Thor, when Thor isn't known on the world, the answer is straight up no. I'll give them alternatives that are present, but I'm not going to bend what has already been established about the nature of the world to accommodate it. When we get into
races that is just as fundamental a part of what the world is all about as the pantheons, history, or nations. Maybe that's where I differ from some people. If you see races as just a variety of nationalities, it might not be a big deal to throw in a country of race x here or there. But fantasy species are as big of deal as anything else in my essential world definitions, and you just can't add your Vulcan to my Middle-Earth.
The issue is one about information.
This happens when a player only knows about D&D in general and not about the DMs world in particular.
If and when the DM manages to write up his world well ahead of the chargen session, I would think fewer players would make demands that the DM feels are unsuited to the campaign.
So this is what happens when the DM underestimates the importance of handing out relevant campaign world info already when first inviting the player.
Otherwise I feel it's only to be expected that a player assumes all PHB options are on the table, since so many D&D campaigns DOESN'T have any particular (strong) flavor.
Exactly this. I always want to talk with my players
before they make a character. I get no pleasure out of them showing up with a developed character and then be disappointed that it has to be disallowed.