I'm going to directly quote user TheTXI's answer from Meta.StackOverflow here to the question "Should 'Hi', 'thanks,' taglines, and salutations be removed from posts?" because I can't answer this better than it was answered there:
I've always been against the greetings and salutations (along with other extraneous clutter) in questions for a number of reasons:
It will leave even less room in the question preview so that we have more difficulty gauging what a question consists of by reading the preview.
It takes time to read and parse through those questions when I am trying to spend my time more efficiently reading through the actual question and figuring out how to appropriately answer it. If I have to start reading all the little side comments and snarky humor inserted in there it detracts from the overall message.
If this is supposed to be a website which is servicing more than just the primary author, we need to think about how we construct messages so that they appear more clearly to those searching on google for questions that match their own. If I am looking for a solution for question X, I want to find someone who had the same problem, not their short autobiography and formalities before getting to that actual question.
This website isn't about individuals asking questions in the most polite manner, it is a repository for important, interesting and useful questions. While adding 'thanks' might be thought of as polite when you initially ask the question, it serves no benefit to someone viewing the question in 6 months time; they just want to see if the question fits their issue so they can get to the answers.
The politeness comes from providing high quality questions and answers, from directing users how to improve questions to allow them to get the best possible answers and by improving posters spelling and grammar to make everything much easier and friendly to read.
The way I think of it is to compare ux.se to Wikipedia instead of traditional forums. Can you imagine reading Wikipedia and each article started with 'Hi, I want to talk about Ford Motor Vehicles.......Thanks for reading, I hope you liked my article, James'. That is unnecessary to the content of the article, it would just be noise.