I'm curious to hear your thoughts on this matter. A friend and I were discussing the playability of a monk. I know it's not a very good class but I really enjoy playing the class. Always have. I understand there are better options. I say it's my character I'll play it how I want. His argument is that other players shouldn't have to suffer because someone wants to play an un-optimized character. I assume he means in combat. So here's the question...
Lets say someone in a game you were DMing is playing a truly terribly built character that they enjoyed. Would let it be? Tell them to make a better one or version of that character? What would you do.
To start with, your friend is basing this on a false premise: that the Monk class is so bad that it makes the rest of the party suffer. This is simply untrue. Monks enjoy excellent saves, good AC, and most importantly their AC is largely consistent, even against touch attacks. Most of the complaints against them have been mitigated by the Amulet of Mighty Fists, the Unchained Monk, the Sacred Fist Warpriest archetype (which is basically an alternate monk), the Temple Sword, and the Brawler (basically a Monk for people who don't want to be Lawful).
Now to the larger question: is the player un-optimized for a specific reason, or just to be bad? Pretty much any character concept can be built in a way that contributes to the group. There's more to Pathfinder than DPR.