The rationale would be that Adams is slightly taller/longer, a better athlete and a better shot blocker, letting Favors play out on the floor a bit more.
It's also based on the idea that Adams can keep improving enough to basically replace the things Kanter does, while trading in one card to get two back. If you're committed to rebuilding, you'd think about this seriously.
Adams + Favors is a daunting front court, and if we got a top 5 or 6 player in the 2014 draft, it creates more value overall.
I think I would do it depending on the 2014 pick I get back. Plus, the Jazz would lose more games this coming season and have their own pick in the lotto. That gives us two lottery picks in 2014 to go with the new Core 4 + #21 (Larkin/Wolters/Rice Jr./...).
The opportunity cost would be picking a point guard at #14, so maybe we make another move to get Dallas' pick.