Very small Poll numbers (2500 participants), but here on WDWMAGIC, Fantasmic is the number 1 night show. See
http://forums.wdwmagic.com/showthread.php?t=56191
I wouldnt say that it is holding together the Studios, but having a great night show is certainly something that has been a staple of the successful parks. Look at IllumiNations, that show propped up people staying at Epcot till 9pm for 20 years!
The announcement doesnt really help anyone but the diehard fans who stay tuned to this kind of information. The vast majority of guests dont care or even think about opening hours and rehabs until they check in. Then they look at the times guide and realise things arent quite the way they should be.