Found the same thing with Ryanair. I think that possibly the early boarders go for a seat near the front so as to be off early at the other end. Not everybody wants the added responsibility of sitting at an exit seat but I doubt this puts too many people off.
I agree with you about the "jokes". Humour is a very subjective art and I think crew sound much better when they come across as mature confident and professional. On the other hand when the airlines emblazon their aircraft with advertising hoardings and protest banners perhaps it is becoming a sign of the times.
