I can only speak for myself, but here goes, in no particular order.
1. Efficiency. With a flame, about 80% of that expensive heat goes to heat the world and not the beer. With elements submerged in liquid, all the heat goes to the beer. Insulation is difficult to impossible with direct flame heat. Very easy with electric.
2. Noise. Ever notice how quiet the world is when you finally can shut off that damn noisy roaring burner?
3. Convenience. The power is just there. It's like changing from whale oil lamps to electric lights.
4. Safety and cleanliness. You can brew indoors without poisoning yourself and loved ones. No soot or fumes.
5. Precise control. Choose mostly manual, full bore automation, or anywhere in between. You can do it with gas, but it is more complex.
The down sides that I can see are:
1. Don't mess about with electricity until you know what you are doing. You can get dead real easy, otherwise.
2. Portability, or lack of. Gas works everywhere. With electric you have to consider voltage, amperage, type of outlets available.
I've just completed my electric setup. I'll never go back to gas.
Good luck!