That's not entirely accurate. He's using Metroid to illustrate Valley 2's platform design and implies that it has good controls by induction. He also uses The binding of Isaac (a completely different genre) for an example of "good controls", which is like saying that Valley 2 should control like Zelda. If he didn't put much thought into it, his post is poorly reasoned and hardly could be described as well-thought out.
Metroid only has 3 directional aiming - upwards, and to the right and the left. You can't shoot down or diagonally in Metroid. Absolutely none of the Castlevania expansions use diagonal aiming for default weapons, and you don't even have control over most subweapon arcs, like the axe. I don't get his point. Even on keyboards, it's very traditional to have jumping and motion on different hands.
Pray tell me which 2D platformer game with excellent keyboard controls puts jumping and motion on the same hand?
Let's go through the first few pages Steam, shall we? Filtering out the games without true jumping (Waking Mars, Nights)
Party of Sin - Nope.
Rayman Origins - Definitely not.
Deadlight - left hand movement, shift to run, space to jump. Yes (mouse and keyboard control)
Giana Sisters - Definitely not.
Cave Story - Certainly doesn't (it has no diagonal fire either).
Sugar Cube - Nope. (Jump with Z or space)
Cargo Commander - Yes - WASD movement, mouse to aim and fire (mouse and keyboard controls)
Trine(2) - Yes WASD space jump, mouse to aim, etc (Mouse and keyboard)
Awesomenauts - Yes (mouse and keyboard)
Intrusion 2 - Yes (mouse and keyboard)
Ys anything - Definitely not.
Sonic Generations - Nope
Cortex Command - Yes (mouse and keyboard)
Noitu Love (both) - Nope
Notice a trend? Every single game with movement on the same hand as jumping has mouse controlled aiming and firing. Games which have keyboard only controls as a rule don't put jumping on the same hand as movement.
Valley 2 is keyboard only, Valley 1 was keyboard and mouse. See the difference?