Imagine if there was some kind of runtime the browser shipped with that could let developers create all kind of applications that are downloaded and run on demand. That would be pretty cool.

They already put entire desktop environments in some two decades ago. It never took off.

With good reasons at the time -- browsers were slow and heavy. Now we have (among others) the V8 Javascript engine and insanely fast client computers (all of any recent desktop, laptop, and mobile device)

Browsers are slower and heavier than they ever were. V8… you could argue it's faster, if you neglect warm-up time, but even it is heavier.

acknowledged, but in my experience they are way quicker than 1990s / 2000s browsers

Because installing Excel is simple already

Install excel and nodejs. Then evaluate which was easier. I suspect node will win by a wide margin.

Already did. The author found that installing Node.js needs knowledge about the command line while Excel just needs a few clicks of "Next" (I just did it yesterday)

Node.js could improve their installer, would that solve all of OPs complaints?

Partially. OP also wrote that he want's a JS IDE bundled.

Probably.

Having installed excel and node countless times I can safely say excel is harder to install.