Yep, fully agreed. Also finding it interesting how they kept extending and improving this and other patterns throughout the games. This particular one was used in SC1, WC3 and SC2 (and maybe others that I don't know) and you could see the improvements in each one.

(OK, just for fairness: StarCraft also has hidden features that are only reachable through modifier keys, like the entire grouping and command chaining systems - and C&C does have some feedback: They do indicate the action by changing the cursor icon. So there are flaws, but I still find Blizzard's system more consistent and information-rich.)