It's in Game Informer's (Playstation Official Magazine French/Italian) Skyrim article. Sorry if that's not concrete enough for you.
Edit: It was from another mag. Here's what it said though:
You don't choose a birth sign at character creation. Instead, you choose perks when you level up. Each perk corresponds to a star, and the different signs are different perk trees (and related perks). Thus you can choose perks from a variety of astrological signs, lighting up individual stars, or you can focus on a few signs and get them completely lit up. The sky is divided into Magic, Combat, and Stealth regions, and the signs in those areas are made up of perks for those specializations.
So if you can pick perks from the sky regions of magic, combat, and stealth are these seperate from perks say for one-handed blade or axe? Or picking a perk for a skill like one-handed blade just light up a star in the combat region of the sky? Although this sounds kind of interesting I wish they could keep the birthsigns (constellations) and as you pick a perk it corresponds to a certain birthsign, still keeping the different constellations. Obvious ones would be the warrior sign in the combat region of the sky. Or the mage in the magic region. Others would be a little harder to define maybe, but each region (combat, magic, stealth) would have several birthsigns in it. Sliming them down to just combat, stealth, and magic seems unimaginative. But I guess it fits better with their skill window with the constellation behind it.
I may be misremembering since I haven't played MW in a while, but I thought that if you looked into the sky (which I thought was quite stunning) you could actally see the constellations for the birthsigns. If so, removing them seems a bad idea. They may not have been in all TES games, but the last two incorporated them and I think Skyrim and later ones should too. It's different than say, changing combat mechanics to make it work better.
As for the OP, I never really was that successful playing a atronach mage because of the problems you state, but I wouldn't change it except maybe allowing it to regen during sleep. As others have said, it isn't for everyone. Some like the challenge, don't take it away from them because you don't like it. And as another posted Atronach actually works quite well with non-mage/hybrid characters.