Con: LaVine won't help the Jazz' defense
LaVine won't make any All-Defense teams anytime soon. Once upon a time, his individual defense was so bad that he was pretty much an internet meme. He has improved in that area to the point where he can't be exploited as easily, but no team would call about LaVine if their intent is to improve that side of the ball.
What makes the problem worse is that the Jazz had the worst defensive rating in the NBA, allowing 119.6 points per 100 possessions, per NBA.com. Acquiring LaVine would shore up the offense a bit, but the defense wouldn't benefit much from him. Adding him wouldn't help a pressing need.
The point is, if the Jazz want to make a playoff push and not embrace the tank, they need more defensive personnel. Now, they can acquire LaVine and then add players who could improve their defense. Knowing how big LaVine's contract is, that would prove difficult.