You're right, they were running it with Flacco, and we all saw how that turned out against Miami (/sarcasm); it's not that big of a part of the offense and it will be something they'll increase for Jackson. The more significant piece I was commenting is any amount of RPO, which they currently don't do any of, and they shouldn't until Jackson is the #1. Throwing that into an offense isn't nothing.
Eh, I think that's just an issue of perspective. Another could be that adding this talent will lead to success in the current system. I don't think you overhaul your offense just because of a couple new receivers, some of which will only be here for a year, or are draft picks. Crabtree is a professional, he'll learn the offense they put in front of him, same with the others, none of them are so dynamically different that you have to worry about scheme change.
I think you're underestimating the amount that everyone in offensive system will need to adapt to his style. Especially down to the linemen, every single one of them will need to keep the possibility that he'll break one off in the back of their mind.
Receivers? If plays break down they need to know what he's going to look to do in space to extend the play. Joe might run up and slide(hopefully) or roll out a bit, but Jackson takes it to another level and it will be a major adjustment.
I was just making a point of everyone putting so much emphasis on what he can do because they saw it in college, and it will die down once real games start because they'll be installing the offense Joe is expected to thrive in on Sundays. I wasn't trying to say any more than that, just the media's reaction and how it's then forcefed out to the fans.