What exactly is "the Metroid experience"?

The feeling of isolation in a planet. Where you have to explore and colect upgrades, learn skills and understand the story and lore with visuals (enviromental) clues.

In that sense, Metroid Prime has the best "inmersion" in that kind of feeling in 3d (Music, escenery,etc)

Super Metroid has the exact same feeling  in 2d, plus the incredible movility options of Samus. You explore in Super Metroid, but Samus is fast and almost unstopable in the end. When the gameplay was translated to 3d . Metroid Prime has to trade movility for ambience because of technical limitations.

Sorry for my bad english.

Immersive and atmospheric music is nonexistent in Dread. Exploration is lacking too. 

Maybe it was for the best he was fired then.

 He ran a porn site on Nintendo's servers and hardly ever showed up for work lol so yeah.

Evidently Retro Studios was able to move on without him.

I mean who hasn’t

 Indeed. While I think Ravenblade seemed like a cool idea. The NFL Football game seemed unneeded (Gamecube had NFL2k and Madden). Car Combat was kinda out the door in popularity. But Nintendo making them focus on Prime instead was the right move. Tho I always kinda wish the concept art for the Mario football (American) game happened on Wii. I get why Nintendo never pulled the trigger tho as the other Mario sports games have worldwide appeal but US Football not so much.

And Nintendo is hypocritical when it comes to adult content. Look up Nintendo Love Hotels.

I mean who isn't