DO NOT create your own launcher, this is a very bad thing. Entering your own account details into random things is a BAD IDEA you should not be asking your users to do that.
Beyond that, we do not host uncompressed libraries, so they are not directly downloadable from our maven.
Our installer downloads a compressed version and installs it. So we ask people use our installer instead of installing Forge automatically. {Plus it is how we pay for the servers, and rent, and food... so...}
Using compressed version saves us ~10TB/day so it's kinda important.