You know, there's a very easy way to get the best of both worlds. You cut and paste what you want as usual, but instead of adding quotation marks, you highlight the text and click that little "word ballon" icon in the formatting menu. That will automatically surround your text with the quote tags. Or you can click the button first, then insert your text between the tags.
Try it. It's probably even easier than using quotes. The formatting buttons are your friend! Here, I'll use it right now:
Yeah well I don't like netiquette...I don't obey it heh
The problem with not using netiquette is that you're not communicating effectively. It's like shouting in a quiet room when everyone else is speaking calmly. People will be so distracted by why you are shouting, that they are not likely to listen to what you have to say.
Also, people may not even read your messages if you don't follow normal posting rules... For example, whenever I see a huge block of text with no periods or paragraph breaks, all in lower case, I won't even try to read it. It looks ignorant, plus it gives me a headache!