User blog comment:LivesByProxy/Shaco - Champion Update - Season 6/@comment-26854318-20151007110239/@comment-26815373-20151007163553

It's intentionally to keep Shaco mana hungry enough that he can't easily be a ranged champion - if it wasn't this way, he could lane a lot easier, potentially pushing out other champions. The cooldown upon toggling off is for this same reason. Shaco juggles his daggers, you juggle his mana costs and cooldowns. ;p

And as far as his laugh, think of the flavor. *-* Sona makes them dance, Shaco should make them laugh. Not having such a feature is a huge missed opportunity on Riot's part, imo. Also, LeBlanc, Teemo, Vi, and Blitz.