Sort of. I think it's fairly easy to see what trends work and what trends don't when looking at the history of the game. It's also easy to tell that sometimes the developers aren't making decisions from a place that necessarily is good for the game. While I appreciate what they've been doing for the game lately, and have found that there's been massive improvement in both their overall balancing, itemization, and response to player feedback, it still sometimes feels like they make changes via a blindfolded darts competition. The recent Guardian red-line changes are an example of that. My sentiment on that, of course, is not me hating the game or the development team. It's the opposite. I recognize their efforts to make the game that I've stuck around for almost ten years to play better, and any criticism I may have towards their decisions comes from a place of wanting this game to be the best and most successful that it can be.
While this change is indeed radical, I'm not entirely certain it's in response to anything in particular. It may simply be a miscalculation, or a change for changes sake. We all know that Turbine sometimes has a history of fixing things that ain't broke, as the saying goes

. The fact that requires, as you said, no rep, quest pack, or grind, makes it a complete outlier in terms of what we know to be business as usual in the scheme of in-game itemization. Unless we're looking at a level cap increase within the next few months, nullifying both the raid as well as all landscape content, it simply doesn't make much sense, regardless of any under-the-radar statistics that Turbine is privy to. I also think that they may not have as much of a "key" as you think they do, and to a certain extent they're trying to figure out what works just as much as any of the rest of us are.
In that case, it's our job as players to try to give them the most unbiased, well-thought advice that we can, with the good of the game in mind. I think everyone who's posting here shares my love of this game, and I hope everyone can keep in mind that it's not about any one group of players or another, but rather what we can do to keep this game active and successful.