Somehow those numbers don't tally with your list of equipment. 50mA sounds more like the quiescent current for the listed devices. The 2 7 segment devices alone IF displaying anything would be drawing 5mA/seg typical minimum current, assuming you are displaying 6 1's... is .005 X 2 segments X 6 digits = 60mA. A typical backlight whether EL or LED will draw 100 mA.
15V - 3V3 = 11.7 X .05A = 0.585W so the 'basic setup' doing nothing causes the regulator to dissipate 585mW, add 100 mA from the LCD backlight and the power dissipated is now 1.755W and that is well past the point where a prudent engineer would have added a heat radiator of some type. My break point is 10 deg C + ambient above that and I make available a 50mm X 2mm piece of aluminum. Everyone is different and if what you have works for you then by all means go with it... The numbers don't seem right to me so... My $0.02's worth.
Bob