I agree completely with the OP. Bringing in Rex, and going back to the defensive scheme of 2013, and letting Schwartz walk is a step-backwards. Period. The proof is that our defense was much better in 2014 than 2013. Moving Dareus to DE or NT is not his strength. The 4-3 fits our personnel better. Mario now will have to basically play OLB, which he is on record as saying he doesn't like.
I'm stunned at the overwhelming percentage of posters who like this hire. Logic says it is backwards. We took our strength (defense) and changed it, and didn't address our offensive weakness nearly enough. Those who think Roman is a savior must not have watched SF games much.
Mike Shannahan or Gary Kubiak would have supplied instant ground game improvement, along with keeping Schwartz and the defense the same, would have made more logical sense.
A "flashy" hire that doesn't address your biggest weakness, just because a guy makes for an entertaining interview, is ridiculous.