Oh and to answer your questions directly!
I am happiest thinking of kata bunkai as responses to common violence. This is possibly due to my old karate clubs focus on self defence. I always enjoyed kata but have to acknowledge the 'poetic license' I allow when applying bunkai.
I too do not 'like' karate attack based bunkai. I acknowledge I would be a hypocrite to say it was wrong or I was right though. I can though see reasons why it is practiced. For one, it allows for safe and basic practice. Also it should be noted that not only 'low competence' places teach bunkai in this manner. I have seen it taught at very respectable karate dojo's.
Interesting that you say nobody steps forward and punches, so why teach it, when that exact movement is so prevalent in kata.
My main problem is with kata being 'heart' of karate, even though it's purpose and application are so vague and in fact unknown. (I'm sure some will claim this its strength!!!!!!!)