I want to just click the shortcut and have it automatically launch, going straight to the game menu instead of having to click the play button.
OK, I tested a macro for my mouse and for my computer. I boldened the 'my' because I most probable have different system spacs and OS then you do (if you don't have a HP250G3 Laptop with Windows 8.1 and the same applications I have :D )
What it does:
Goes to the desktop, if not already there (moves pointer to the down right corner and clicks),
Doubleclicks the Minecraft Launcher shortcut icon (again, by mouse, even though not needed)
Waits 12 seconds
Presses Enter (More safe is to do this by mouse, what if you acidentally unclick the window)
Instead of hard-wiring this into your computer, use a macro recorder - a program that you run, it sees what you did, then saves it. You can then run it for getting exactly what you did before. For getting a macro recorder, what you could do is check what's on Google. What I found is: