Bassic - I think you are absolutely right in what you say in para 4, - mainly because I agree with you :)
But seriously, I find myself getting unreasonably irritated by people that I consider to be below acceptable standard - and I think that the main reason I get irritated is because they are playing with "my toys" IN MY SPACE. Very often we are jostling for position in a busy session, and an inept player can be using up time that we better players could be filling (that is to dramatise the feeling a bit - but I'm sure a lot of people feel the same to some degree). So the answer is maybe to make more space (more sessions) so that we don't feel so anxious & competitive?