Writing for The Master’s Seminary, William Barrick explains the problem of over-occupation with word studies (scroll to page 19 of the doc):
Study of the words alone will not present us with a consistent interpretation or theology. This is one of the misleading aspects of theological dictionaries/wordbooks. One learns far more about obedience/disobedience or sacrifice and sin from the full statement of a passage like 1 Sam 15:22–23 than he will from word studies of key terms like “sacrifice,” “obey,” or “sin” in the text.
He explains briefly why word studies are easy and popular. But he shows with a few good examples that they simply will not do. We do far better to learn how to study passages than to study words.