Okay, but why? No offense, but do we really need another FTP client in 2016?
I think there's a very valid exception -- well, there's many, but here's my favorite: "Don't reinvent the wheel unless you are trying to learn how the wheel works."
See I like that phrase. Gives you a lot more creative license to just redo what has been made if you are curious about it. What if at the end of that learning experience you have a nice, fairly polished wheel and you'd like to share it? Maybe for e-cred, maybe for criticism, maybe just searching for praise.
I'd say that the underlying motivation is irrelevant. We as a community should be less skeptical about this stuff, we really need to learn to just be happy for people, maybe even give out some praise.
So on that note. Nice job OP! I really like the font choice, and colors. UI wise this might be the best FTP client I've seen.
Also I wasn't a fan of how every client looked like they were straight from XP. I used this as a way to get familiar with Electron, as well.
Lastly, it's open source so people can add whatever they want to it. I have a few ideas that I would love to be using myself (image previews, in-client file editing, etc), and I'm sure other people have their own features they'd want - and they can add them now.
You keep repeating this line. If a FTP client has received heavy usage and development since the XP days, that's a good sign, I think. It proves that it is well used, tested, reliable, and capable.
I'd much rather have a program with a passable UI that is lightweight and does everything I want, than one that has an unjustified resource usage to feature ratio.
There's no shortage of clients. Personally, I think you shouldn't use FTP at all, but you do you.