Quote from yuri21
They're just cliches and stereotypes and can be extremely annoying since it's like "someone with this kinda name/character must be completely submissive or aggressive or has to behave as such and such". However, it's far more interesting to find BL that doesn't really adhere to these "stereotypes".
I agree with you yuri, since they are sterotypes used in MOST yaoi, not saying all of them are like this, but most of the ones I have read always have the uke as kinda wimpish and small...and the seme more agressive and bigger....also the dont switch, its like "oh well your the uke..so your gonna stay that way" kinda things in manga...but in RL gay couple usualy aren't like that....so the whole uke and seme thing is just making somewhat of a fictionally based stereotype.
Though in RL I have never actually heard anyone be refered to as uke or seme...just top or bottom. But eh...i see them not so much derogatory, but more fictionally based....