I was going to post on the process for selecting new DumDum flavors in an effort to more broadly answer "why the crap did they get rid of cream soda?!" But instead, their entire FAQ portion of their website is worth a Copy-Paste
The Mystery Flavor™ is a secret. We can only reveal that the Mystery Flavor continuously changes and is not limited to current Dum Dum flavors. It's up to Dum Dum fans to guess the flavor of these mysterious pops.
Spangler Candy does not have a set schedule when new flavors come out. We have a total of 16 flavors + the Mystery Flavor™. We generally keep 9-10 of the "original" Dum Dum flavors in the bag, while 2-3 new flavors take turns rotating into the flavor assortment. New flavors in the assortment will be highlighted on our web site.
We start with a list of about 400 potential flavors. Our Quality Assurance flavor lab is continually producing flavor samples for our employees to taste-test. Our employees rank the samples from 1 - 10 based upon how much they like that particular flavor. Flavors that rank high then move on to an evaluation by our Marketing department. If the flavor meets all of the criteria of the Marketing department, it can be recommended as a new flavor to be added to the assortment.