I can honestly say that those people you're talking to are taking those games way too seriously.
For God's sake, it's a game. People can do whatever the fuck they want to in a game, within the limitations of the programming. You should not feel ashamed because your build was not ideal. Sure, maybe if you made the game a bit hard because you made some bad decisions for skills then yeah, you made a mistake. That sucks, but it's a game. You shouldn't have to go and restart a game just because you did something different. I've noticed this a lot. I used to play Diablo II a bunch, and I realized that my build for a Barbarian character was, in some ways, the exact opposite of what I should have done.
But you know what, I still enjoyed the game, even after I realized that my build wasn't "good". I beat it, I had a lot of fun, so I really didn't go wrong when you think about it. I played the game because it was supposed to be fun. I had fun, so there was nothing wrong with how I played it.
My advice, don't worry about that too much. If you think you want to get into it again but don't want to be bothered by haters, maybe read up on some builds before you go. But as long as the game is still fun, well, mission accomplished.