- A dedicated menu button on mouse is hard to discover. Mac's brilliance is that you can start exploring the UX right away without any prior knowledge of which button does what. It also prevents you from examining your options without needing to click anything. I don't think saved screen real estate is worth it. Mac & Windows did away with always-visible menu bars just fine. Remember how Windows 8 tried to hide the start menu and how it had turned into the worst UX experience in the last decade ever. Visibility is important for discoverability.
- "Drag & drop" has too much user friction. It's hard to discover, it's hard to apply properly (many beginner users think that leaving button mid-drag is okay for a short little while). It's impractical because you usually use your apps maximized (for the maximum real estate, remember?). It requires you to have the file visible and easily accessible (consider cluttered desktop icons). I stopped using drag&drop a long time ago, and resort to Copy/Paste function of Windows Explorer for copying files, which works brilliant.
"Drag & drop to open" has other issues too. For one, there is no orthogonality between open & close. Do I drag away the icon to close the file or is there a standalone "close" option without an open?
They might be novel ideas for their time, but I don't think they provide good UX.