Quote from smilingsynic:
Many traders like certainty, and analyzing volume patterns does not always provide that certainty. Sometimes the market goes up on low volume, and stays up. It would be easy for a trader to simply throw up her hands and say, "Volume is unreliable and hard to figure out; therefore, it is not worth my time."
Some traders are more left-brain in their analysis, and some are more right-brain, and some are pretty much both. Many are uncomfortable with discretionary trading, and volume analysis fits into that category.
I don't take offence at those who do not use volume. All I know is that volume is for my daytrading essential. I would not want to be on the wrong side of a move with significant volume behind it!