Because videogames are made by videogame nerds who don't know how to write a good story.

However, a big problem is that you can't just tell a story in videogames. Either you let players do what they want to do (making telling stories very difficult) or you script everything perfectly and you make the game boring. Obviously those are two extremes, but you can see how developers aren't just telling a story, they are making a game.

Honestly, I think Miyamoto does the best job telling stories. Quick, simple, and he never lets you down

I have to disagree, I think one of the only flaws left with the Mario series is they subject you to a utterly retarded story for a few minutes.  The beginning and ending of SMG2 were just painfully dull and they should just cut story out of those games entirely.  Would make all the Ninty fans happy because they're always talking about how story is pointless, and I won't have to sit through a children's story book before I can get to my platforming.

Story: Why the F does it matter?

This. I pay 60 bucks for gameplay, not story...

My problem is that so many games take themselves so seriously when it comes to story and pause the gameplay for the cinematics and dialoge, yet story is still shit...hence it wastes my time and ruins gameplay pacing.

Gears of war, God of war...looking at you.

The bigger problem than whether the story is good or not is that they give you a story whether you want it or not. My best guess is the story in most video games is a reflection of the designers insecurity more than anything else. You know those annoying people who justify everything to you? "Like I did the washing because it was warm outside and then I had a shower because I was sweaty from doing the washing and then I did the washing again with just the clothes I was wearing because I didn't want to leave clothes on the floor in the basket when I had just done the washing as that would have made it feel incomplete". A game like Doom never required justification to slaughter thousands of demons and so it should have remained.