Just so.
DM: "In a world without drow..."
Player: "But the drow are in the PHB! They're my favorite! I have to be able to play a drow!"
DM: Sigh.
Every single change from the PHB is a fight waiting to happen. Players have expectations set by the books. The referee can either conform to those expectations or get ready to fight. Doesn't matter what it is. Doesn't matter if it's something anyone at the table wanted to actually use or not. Someone will fight you on any change you make just on principle.
Yes, please.
Depends on the prep. I like rolling on a bunch of tables to see what's in the world. That's my prep.
As long as you don't use the official rules to make monsters it's great. Use the 5E MM on a business card and/or action-oriented monsters and you can make fun monsters in minutes.
That's the one that's the biggest sticking points for me. Arguing about ranges. Arguing about how many spells a PC can cast in a round. Thanks internet for making my players think they can cast like 9 spells in a round, btw. Arguing about LOS on spells. Arguing about the legality of some stupid power gamer build. Arguing about cover. Arguing about carrying capacity. Arguing about whether their characters and their pack animals actually need food. (Yes, really.) On and on and on. The players expect the referee to run the game like a computer would. With the same precision and perfection. Input, output.
I was creating a custom game world for Pathfinder 1e. My roommate helped me compile all the rules changes and made a PDF for them, with full art and all my descriptions of the unique races and rules, it looked very professional and easy to read.
I gave the pdf to all my players to read.
Day One: "Uh, why are there no Ninjas?"
"The area of the game you'll be playing with has no real contact with cultures that are anything like Japan or Asia, so I felt there was no reason to have Ninjas or Samurai."
"You could have Ninjas, just call them something else."
"I could have, but I didn't."
"Whatever."
Day Two: "Hey! No Paladins?!"
"I'm tired of all the arguments about Paladin restrictions limiting roleplay, and I honestly don't want to feel like I need to step in and dictate how you play your character. The fact that the Paladin has built-in restrictions on behavior that I then have to enforce is then self-defeating."
"But I want to play a Paladin!"
"You can play a Cleric and be a soldier for your God. Or Good."
"But I wouldn't be able to Smite."
"Take the Destruction Domain."
"Couldn't you just let me play a Paladin without the restrictions?"
Day Three: "Hey! No Dwarves?!"
"They exist in the setting, but won't be encountered in the starting area."
"So I can play a Dwarf then, I'd just be the only one?"
"No. I want to keep Dwarves a secret for now."
"Could I be a Dwarf with amnesia?"
"AUGGH!"