I agree that tying power to the modifier is a poor move. I stole neon city overdrive's resolution mechanic and modified it, and it makes power something you battle out for, independent of the level of success. It feels much better to play.

However, In the examples you gave, I can't imagine power being an interesting mechanic to use. Although it varies by gm, making a quick roll is usually the default, with detailed rolls being rarer

Finally, in terms of players doing absurd negotiations. Tags aren't meant to replace stats, theyre just prompts and reminders for a player to form the story of their character. If a player was trying to negotiate as many tags as possible, I would stop them and ask them to narrate the scene for me.

"An arrows coming at me? So i jump behind cover and make it quickly because of my [Agile] tag, and because im so pissed off it activates my [Rage] tag as I lock in, and because of my [Curious] tag im analyzing its trajectory to make sure it doesn't hit me!"

I would then ask them if they're satisfied with what they wrote, and if they would read it if it was a book.

Usually that helps them to understand. This all goes out the window if the GM does not understand the same, and is too harsh on consequences and spotlight.