While I do agree that the current magazine content is inferior to the earlier issues, I feel like the change was more due to the rise of the Internet than anything else. My favorite thing about Nintendo Power back in the day was the way they would devote 10 - 12 pages, per issue, to the hottest games of the month, and fill those pages with maps, hints, and strategy guides. Hell, over the course of a few issues, they provided strategies and walkthroughs to entire games (Secret of Mana and Super Metroid come to mind) and I could always count on NP to help me through a game... or, at least, help me get started!
What changed was the general lack of game strategy and hints, and a bigger focus on feature stories. They realised that they couldn't compete with in-depth Internet reviews and sites like GameFAQs, so the focus changed more to previews of unreleased games, features on game-related goods, and spotlights on fans and fan creations. It wasn't a terrible magazine the last time I subscribed (around 2009 or 2010) but it was clear the entire format had changed.
I'm sorry to see them go, but it's time. If GamePro has left the building, and EGM's gone through it's on-again off-again printing cycles, then it's only fair for Nintendo Power to suffer the same fate. It's a shame, if for nothing else, that there are so few dedicated game magazines left.