DAB+ doesn't use less power if all they do is fit more stations in. It has better error correction apparently, though in practice I would say there is no difference if you have a weak signal compared to MP2. Also DAB suffers from poor bitrates used in order to cram in more stations and the audio quality is bad because of this. AAC+ should have solved this problem but they are using too low bitrates again to fit in even more stations so we are back to square one again. Its all down to cost and profit. Fit more stations in at low bitrates - that means more revenue for the DAB TX operator. Have 1 MUX with maximum number of stations before it becomes totally unlistenable compared to virtually unlistenable, instead of paying for more MUXes. More TX's mean more electricity costs.
I'm surprised it's taken this long to start transmitting in AAC+ on satellite. MP2 is very old tech, some of the stations on 28 E are only 128K and sound pants, its the French, Dutch and Germans that use better quality and that goes for TV pictures too.