Oh I see... yes, simply giving orders from the galaxy map is the way to do that. Going planet by planet would be maddening, indeed!
And yes, there is no way to change the binding to just right-click to go into the wormholes with units. The keybinding that is defined is a modifier that gets added with right-click, so you could make it Z+right-click instead of ctrl if you wanted to. But trust me, you would never want it to be just right-click -- we had that in the original game about 10 years ago for a while, and it was chaos. There is often fighting right on top of a wormhole, and we were sending our ships through to the other planet constantly. It was chaos!
But by sending ships on the galaxy map, you just have to right click the planet you want and they're off to the races. No need to hold any button.
Hope that helps!