This is actually a really good and valid question, because I wrestled with this decision for almost a year before going with this splitter. Sorry, this is going to be a bit longer post, so the TL;DR croud might not make it all the way through it.
While the price is quite a bit higher vs a gas model in the same size range (20-25 ton) there were several factors that ultimately made me go this route.
1. Noise and fumes. Several years ago when I had a wood furnace in my old house, I bought a cheap, used gas splitter and after a couple hours of using it each time, I was dizzy from the exhaust fumes and my ears were ringing, sometimes even when I wore ear plugs. The electric motor, while it does still make noise, is much less obnoxious than a gas engine ringing in your ears all day. I can even use it without ear plugs, though I'll wear them if I'm going to be using it for more than an hour or two at a time.
2. Gas and oil and all the related issues that come with them. I will not have to do an oil change on this splitter every so many hours. Sure, at some interval I'll need to change the hydraulic oil, but certainly less frequently than engine oil changes. But the biggest motivator here is not having to worry about a carburetor getting gummed up with bad gas, from the ethanol that is in all the gas that's readily available (at least here in MA. Can't get non ethanol gas at any stations). I remember having to pull the starter cord over and over and fiddle with the choke and dump gas in the carb to get that old gas splitter to start. Now, I just push a button and the electric motor springs into action instantly.
3. Supporting American companies and American workers so they will be around to make quality products in the future. This one is a little more complicated, because it's very compelling to spend ~$1,000 less and just get a gas splitter made overseas. Swisher also makes gas splitters, so if you will be splitting your wood somewhere further away from your house or garage and can't plug in an electric one, gas might be the better option for you, but again an American made gas splitter will likely cost more than a cheap one made elsewhere. I guess what it came down to for me was that at some point I feel like we have to invest our money into high quality American made products to keep all the manufacturing from moving overseas, so there will be good jobs for the next generation of Americans here in the US. I was willing to pay more in the end for that.
Also, I knew I was likely going to be doing most or all of my splitting in the area beside my garage which has power easily accessible to plug into. I also have solar panels and have excess net metering credits that I can use to power the electric splitter. Don't have to spend close to or over $4/gallon for premium gas for it.
