At glance, most coverage of this is a bit misleading as it leaves out a few key points.
* It's not offering CSU credit so much as transfer credits to be applied toward CSU. That's great if I am already attending or plan to attend a school in the CSU system, but it's roundabout at best and useless (in terms of credit) at worst if I'm not.
* You're required to complete a proctored test via Pearson after completing the MOOC for a certification in order to receive those credits - another complication.
* I wondered why I don't recall hearing about this - CSU announced this option in September 2012, through Udacity. Udacity was only a bit over a year old at that point while EdX and Coursera were still in their infancy, 4 and 5 months respectively. There's much greater awareness of MOOCs today and moving forward.
It's purely anecdotal, but my estimation is that a majority of serious (make an effort to complete and pass the course) MITx students would have interest in a credit option.