Logic of Mojang:
Lets take a simple sandbox/survival game and make it into a hardcore RPG! Because there can be never enough RPGs in the world!
New logic of Valve:
Lets make the best games ever, despite the fact that we can't count to three!

And on a related note, I have a theory about HL3: Half Life meets Portal. In the end of Episode 2, you see on the video cameras the lost ship Borealis with and Aperture Labs crate. My theory about the anticipated FPS is that the ship contains materials to build a super portal; just like in the resonance cascade (Black Mesa, HL1) and the Citadel implosion (City 17, HL2-E1). Of course in the end of Episode 2, you destroy the Citadel super portal, but the Combine will just make another at the Borealis! That would also explain Eli's last words before Advisor URB-SEC-17 (Wallace Breen?) sucks out his spinal chord: "You have to destroy that ship!" But what if in the Aperture crate is a hibernation room; with CHELL in it. Mind blowing stuff.
But I could fill up a whole page with HL3 theories, but I won't.