This is apparently an undocumented change in CC2015.
Preferences -> General -> [change] Apply to Content [to] Adjust Scaling Percentage
I have no idea what else this affects, but it allows you to scale tables with the frame as with previous versions.
The biggest change in tables in CC 2015 is the ability to add graphic cells. Although I've never see it mentioned or documented, I'd better it has something to do with that change. Because graphics cells are a pretty major change.
Thanks for reminding me about the answer to that question, which has come up here before!
Changing the Preferences to "Adjust Scaling Percentage" will how everything in your document is scaled. I find it necessary sometimes when InDesign is unable to scale some items like tiny shapes, but using Scaling Percentage results in things I find weird and cumbersome. For example, if you put a 2 pt stroke around an image that you scaled to 78% with the "scaling percentage" preference on you will actually have only 78% of a 2 pt stroke. So if you want to match the stroke sizes in a document filled with odd-scaled boxes your math chore would be enormous.
Switching back to Apply to Content in a document does not revert everything to how it was before, evidently, the document keeps % scaled objects at their scale percentage even when Apply to Content is switched back on. So you may be getting only 78% of your stroke, 78% of your font size, etc., depending on each object's individual scale percentage regardless if you switched back to "Apply to Content."
Therefore, I know it works to use scale percentage but I think there's a valid reason that "Apply to Content" needs to work for table again.