I've noticed that. You know what STILL pisses me off? You can't pause in singleplayer. You've never been able to. And you probably never will.
Also, you have to hit "x" you get your other 6 hotbar slots. What's more annoying is that each "slot" has a left and right click slot, but many things count as two-handed for no sane reason. Sure, blocks make sense. You left-click to place as solid blocks, right-click to place them in the background. But torches and platforms don't do anything when right-clicked, so them taking up a full slot just makes the more awkward hotbar mechanic extra annoying.
On a more positive, mod-related note, I'm still more tempted to do the stealth version of my idea. D: