Look at this from another perspective:
If you decide not to keep Cutler, what is Plan B?
You're going to start over at QB when you have Matt Forte, Brandon Marshall, Alshon Jeffrey and Martellus Bennett and McCown is talking about retiring?
The front office had little choice and Cutler actually had one of his best years statistically. Chicago's bigger concern is the lack of any defense.
Plan B: Build around a new quarterback. Houston is doing it, with the same caliber of weapons as Chicago's. Add in the fact that they just paid Schaub last off-season, they're making the right move by moving forward with someone else. Schaub isn't a winner. Plus, this year's QB class is deeper than years previous, and one or two decent QBs will be available for Chicago to pick. Oh, and Cutler resigning for 18mil directly removes funds allocated for improving their D, or in fact, keeping it together as they'll lose guys like Charles Tillman (good for us).
Cutler is not an elite QB, nor is he second tier. Romo is terrible during the clutch, but he's light years ahead of Jay.