Is there any way to make my MacBook start up only?

Hi, is there any way to make my Macbook start up only, when I tap one specific key (like an on/off button)?

As it is, there's no way to verify wether it's shut down or only sleeping - hitting some key will inevitably start it up.

Even more: if you leave the office for the weekend, consciously shutting down the Mac but then realise, the charger cable is still plugged in, it will start up again by simply removing that cable... seriously: how stupid is the person who has designed this?

[Re-Titled by Moderator]