As eykanal stated, a rant is not allowed, but there can be legitimate questions about ethics/legality. For the buggy code question, interpreting it as "is it ethical for a professor of a course on X to have some issue that makes a lot of the coursework / grades being based on the ability to use/understand Y" is an interesting question that is worth discussion.
On the other hand, the attendance question is mostly a rant. There are related questions that can and should be asked. For example, asking why some professors care about attendance is fine.asking why some professors care about attendance is fine. Also asking about whether it's ethical or against (standard) university polices for a professor to base a certain amount of one's grade on attendance is fine. And even the question of should professors care about and grade student attendance is an interesting pedagogical question.
However, I don't think "How to deal with _____" questions should be allowed since they usually have standard answers. Did the professor break policy? Gather evidence and tell a higher authority. Was no policy broken? Talk to some friends, get some support, and try to do as well as you can given the situation you're in.
I don't know of a clear and concise way to put this distinction.
