The Constitution of the United States started off with only 7 articles and 21 sections that took up only four handwritten pages including signatures! 4 pages! But to that we added 27 amendments.
Today, the United States Code, which is all of the laws in this country, fills up around 80 volumes of books, nearly 800,000 pages, and this doesn't even include the Federal Regulations. In 1942, the Virginia Code was a single book that had 2800 pages. Today, the Virginia Code is a 25-volume set of books with 15,000 pages, nearly 20,000 separate laws! And that is just Virginia!
But, let's not think for a moment that we are the only ones to take something simple and make it complex. God gave the Israelites something simple to follow, the Ten Commandments. Just ten simple rules to follow. Nothing complex about it. But were the Israelites content with just ten commandments? Oh, no. They ended up making 613 separate commandments, 365 negative and 248 positive. Sounds like a lot doesn't it? Try following all those laws in order to be considered faithful and righteous, and you probably thought the original ten was hard enough.
For the lawyer and the Pharisees there was certainly a complex issue at stake. The Israelites were under assault from a man who claimed to be God, and who did God-like things. But this man was a Jew; he should have known better, no one is God, but God. Yet, he was a man who knew and quoted the Hebrew scripture, who knew the laws and commandments better than any religious leader.
The Pharisees had to put a stop to it, the situation was getting out of control, it was becoming too complex to let it go on much longer. This man must be stopped and the only why to stop him was to discredit him. And what better way to discredit Jesus, the Jew, than to ask him such a question, on a complex issue about the greatest commandment, that any answer he gave would spell defeat.