On a matter of principle, it is not shocking to me that it is so big.
The offline installer has to bundle data for all supported products, platforms, languages and dependencies, even the ones you don't need, because you can't tell in advance. The online installer will just download what it needs.
1.2GB is absolutely ridiculous and I hate the bloat we see with pretty much all modern software today more than most people, but I have decided not to complain about it for once :) Know that it doesn't mean I think less of it.
Maybe there are some fancy animations illustrating RGB effects and stuff like that, these can add up, and I can almost (but not quite) excuse them if it is the case. At least, video animations are not a mess of frameworks and libraries that eat your RAM and CPU and introduce vulnerabilities.
The offline installer has to bundle data for all supported products, platforms, languages and dependencies, even the ones you don't need, because you can't tell in advance. The online installer will just download what it needs.