What is the point of the macOS menu bar item?

Agreed, this is a poor experience. Not everything happens in a browser! There are also valid reasons for using browsers without the plugin.

There are cases where sites require more than username/password/MFA (for example, AWS requires the Account Id for non-root users before displaying the email/password form) but Quick Access doesn't allow quick access to these items...I have to click through multiple levels which ultimately requires me to open the full desktop app...might as well use spotlight and forget all about the menu bar at that point.

Quick Access should show the full record without requiring any other clicks or keyboard shortcuts. It should mirror exactly what the browser extension does. That would make it actually "quick" ;)