The one plus for me is that it'll be easier to come back to the game after not playing for a while. The revolving door makes the game a lot more accessible for new and returning players.
I definitely get the feeling that the game is simply not big enough, there aren't enough cards to warrant standard formats. Even so, every expansion and adventure has generally increased in size, and when the last expansion comes out this year, that will be 3 expansions and 3 adventures, plus classic, which is a lot more cards than what's available right now. It also weeds out a lot of the extreme kinds of cards over time, like right off the bat, naxx and gvg are headed out. A lot of those cards weren't terrifically thought out, like you could tell the dev team was still pretty fresh at the whole card making thing. That in turn actually makes quite a few decks that aren't strong in the meta now to be perfectly viable in the future.
That brings me to another gripe I have about this actually; why is Classic staying forever? Some of Classic stuff is much more offensive than naxx and gvg, and frankly I think some cards from naxx and gvg should stick around. Personally I would rather see like a "Kraken" set for this year, with a mixture of previous cards, and with every standard rotation, the set would update and it would be a different rotation. That way your old cards aren't necessarily useless forever, and it gets around OP classic cards without necessarily needing to nerf them (though I think fon/savage roar should be nerfed anyway).
I guess I don't entirely agree with the changes, but at the same time I'm not against it. I'd like to see what changes they make to Classic, and I'd like to see how newer lesser played cards hold up when naxx and GvG aren't around. Ambivilant is a good way to put it.