This change was actually made intentionally because many devices and browsers were trying to auto-login/auto fill in those fields when people visited the main website. This was becoming more and more of an issue with the new iOS using facial recognition to try to pull up the password for it, etc. We decided it was best to have the control panel login be on its own page. I understand that you may feel it's more convenient to have in the header of the entire site, but it's just one click away.