I have been a read-only wikiholic since Summer 2004, when I stumbled onto a Wikipedia mirror while looking for information about group theory. I'm now going to try to participate.
I use to be a strict prescriptivist, but now I've mellowed my views to that of a moderate descriptivist. Nonetheless, I still appreciate certain parts of more obscure grammar when clarity is at stake. For example, one thing that tends to frustrate me is mixing up the nominative and subjective senses of the first person pronoun (I vs. me). People tend to hypercorrect by always referring to themselves as "I" when also mentioning another person. That is, people will go out of their way to say things such as, "Give it to him and I," or "It was fun for Jane and I". Quibbling over that may seem trivial (and probably is), but there are times when using the wrong case changes the meaning. Consider these two:
1. She has more than I.
2. She has more than me.
The first means she has more [stuff] that I do. The second means she has more [stuff] in addition to, or besides, me.
Grammar remains important especially when precision/clarity is at stake. I forgot who to source for this paraphrased headline, but what could be more confusing than "man fends off robber with sword." Now who had the sword?
I also happen to dislike very much the singular they. I by far prefer using he/she or him/her when sex is ambiguous. A better solution, of course, is to construct the phrase in such a way to eliminate the need for this.
For a variety of reasons, I no longer worry about ending sentences in prepositions (it used to concern me a great deal). Neither do I worry excessively about the passive voice and am becoming increasingly aware of the vagueness of English grammar, such as the erroneous rule that none always takes the singular case. English grammar, to me, just keeps getting curiouser and curiouser--now I'm learning that the very definition of a preposition is disputed/uncertain. How untidy.