"Implement a feature XXXX, otherwise I'll use another project."
-
No.
-
Feel free to.
"Without that functionality this project is useless."
It's your personal opinion.
"You're doing everything wrong. Hand over the project to us before it's ruined by you!"
Fork it.
"Your code is awful, we can write a lot better."
Let's write.
"I've done nothing according to the manual. Why nothing works? I hate you!"
RTFM. I don't care how you feel about me.
"You must..."
No.
"I demand..."
Pay money.
Original Russian text written by las68 from habrahabr.ru, translated by Mendor and Silver Dragon