1. It enables a large swatch of people that have never done desktop development (which has a learning curve that is hard to climb if you aren't paid to do it) to build cool stuff and ship it. Without Electron, we'd be left with nothing. If nothing is truly better than something with Electron, then this won't be a compelling point. However I'd rather have stuff that I ignore than to not have stuff.
2. Performance in electron can be decent. It isn't always because of bloat and poor implementation, but that can be true of native apps as well (especially java-based ones). The download size is laughable, but hard drives are reasonably sized these days so this is less of a pragmatic concern, and more of an ideological purity concern.
3. The modern paradigm that React brings to the table can genuinely be a better dev experience than the traditional frameworks. The benefits of "always re-render" would have fixed numerous bugs that I dealt with in UI land regarding state and dealing with changing state. Developer happiness is worth a lot when the project is open-source, unfunded, and done by someone with passion (which is how almost all open source starts).
4. I think it's temporary. There's projects like Proton that are already looking at how to get the best of React/JS on the desktop without the bloat of shipping a web browser with your app. The future looks bright.
NOTE for people devving on electron: Please be more conscious of memory usage and potential memory leaks. Desktop apps are often long-running and you've got to pay attention to resource usage and the memory leak traps that can cause your app to gobble up insane amounts of memory (cough slack cough)