I guess the reason is that it is easier to cross compile by keeping everything in go? I have no knowledge of Sqlite cross compilation (on Linux targeting windows for instance) but I guess it's also possible but it makes build process a little more complex.
Node.js can take advantage of WASM which is pretty handy in some cases.
Getting cgo to cross-compile while targeting less popular architectures can be a royal pain: I was trying to use cgo to add official SQLite to a Go app that I had running on a long-abandoned (by OEM) mips/linux 2.x kernel "IoT" device with an equally ancient libc. It was a sisyphean task that absolutely nerd-sniped me, I spent way too much time on the building toolchains and trying to get them to work with cgo. I ended up going with a Go-version of SQLite
Yes this is the reason. Using cgo to link in c libraries for example is slower and also brings up other difficulties if you want to cross compile. Here's an old link (may be out of date) outlining some of them:
Node.js can take advantage of WASM which is pretty handy in some cases.