You'll get no argument from me that sound and lights should not share the same circuits. But, even one better, they should not be on the same power transformer and/or access panel due to noise cross-talk issues.
My mains, running at WFO, draws 130 amps.
My monitor system, at wFO, draws 30 amps
Backline? Well, not my problem! But it typically stays under 15 amps even on big shows. One show needed 30 amps via 2 15 amp circuits, and while overkill, we did use more than 20 amps worth of power up there, so it wasn't a bad thing!
FOH is a full 15 amps.
Lights can be serious power pigs sa well. Even my small rig, thanks mainly in part to 32 Par48's with 150-watt bulbs, well, and the 2 Color Fusions(they eat a circuit right there) was over 60 amps!
In my case, I'm constantly having to work in environments where power is at a premium, so it becomes a variant of what you said: it's another tool to get the job done. Better or worse(and opinions and facts are valid on this), LED is the way I'm going. Sure, more cost, but less power draw, and I need whatever power draw I can get. At the same time, I am starting to understand and see the harshness in the LED technology, and that's just something I'm going to have to live with based on the choices I've made.
Are incadescent solutions better than LED? Depends on who you ask and what will do the job best. For me, I need more bang for the buck for how much I can put on a circuit, and as a result, I'll have to eat any downsides as a result.
I want to see the LED technology improve, which will in turn drive costs down while pushing features, options and brightness UP. Win-win for those who are fans of LED's.
Should you swap your traditional stuff? Why? I mean, if it's working and gives the results, why screw with a good thing? Use what you got!