If you look at the road map for future development released during the webcast last week, www.youtube.com/watch UTM9.4 is scheduled for release by the end of first quarter. That leaves a very short time for beta.
Also I suspect most of the grunt work will be done on the cloud infrastructure and they can always add minor tweaks to the UI later on in future releases if needed to refine the sandbox functionality so there is really not much to beta test.
The other improvements like STAS and WAF cookie signing although important can only be tested by people who use those functionalities so they probably are not expecting much feedback on that.
Plus a soft release after the beta will give them almost two months to iron out any problems hopefully.
