The article is good, and I also like your banned and restricted list better than WotC's. That said, a few points:
You mention that this is hard to define, but you don't actually give us your definition. It feels like you're using the old definition of "interactive = creatures" in your reference to slow and durdly decks.
What makes more sense is to talk about "interactivity" as being a scale that gets set based on the two decks at issue. The question is: what vectors are the decks using for resources or as a win condition? Creatures on the battlefield? The graveyard? Life totals? Cards left in your library? No single deck is ever "non-interactive" in a vacuum. It is only "non-interactive" if it is paired against a deck that is ignoring its preferred vector.
Example 1: Dredge is non-interactive if any only if the opponent is not interacting with the graveyard. If you're full of graveyard-relevant effects, like a in post-side board game, the deck is very interactive.
Example 2: Vintage combo decks are non-interactive if and only if the opponent is not able to interact with or clog up the stack. If you're full of counterspells and/or sphere effects, then the game is very interactive.
What I see too often is people hand-wave the word "interactive" to mean "decks that don't interact using creatures on the battlefield." I think people do this because (1) creatures are central to the design of the game, and (2) creatures automatically interact with other creatures. So, there's a bias in decks towards making sure the creature vector is covered.
So, I'm having a hard time with your discussion of Trinisphere as "non-interactive." As you point out, big mana / midrange decks or decks with first turn countermagic interact with it just fine. Are you not really saying that you simply don't want a format where people have to pack Artifact Blasts or Annul? I'm not saying these are bad things to want, but anytime you ban something as "non-interactive," what you're really doing is saying "a format that interacts primarily on this vector is not a format I want to play."
I don't like your reasoning here, which basically mirrors WotC's reasoning that they want to keep restricting the best card out of shops until it stops being a good deck. This sounds like a giant exercise in futility. Every time you restrict the best card, the deck just re calibrates and gets a new best card.
Here's a serious question: can you build Highlander Shops? I'd love to see someone try this out because I suspect that you could. And, if so, that pretty much blows up any idea of trying to control the deck through restrictions.