1) I don't like when people are so sensitive that there's no room for a harmless joke.
The joke might seem harmless to you (because your are privileged[1] to think so), but it doesn't mean it is for everyone. Also, if the joke is based on any kind of prejudice (the teller being aware of it or not), it is in fact harmfull as it only helps the status quo, while a number a groups are putting tremendous effort to disrupt said status quo in order to do something about prejudice that is affecting them.
2) there's so much social ineptness
Social ineptness might explain it but it doesn't justify or excuse it.
[1]: http://finallyfeminism101.wordpress.com/2007/03/11/faq-what-...