I can definitely see where you're coming from and I agree with a lot of it. This is simply my preferred play style. I'll have to try doran's ring, but I like sapphire crystal simply for building items.

Sorry but have you even played the new Ryze? Your item path seems good (for a bruiser mage) but your runes, masteries and advice about laneing is way of in my opinion. I know its new and all and whats the best choices is up for debate, but i dont get it.

You say that you should just hug tower and farm? That is in my opinion so wrong with the new ryze. What you want to do is trade. Proc the passiv and trade. You will win everytime. Especially against the typical melee top laners. proc passive -> qeqwq or qwqeq aa -> let the shield take the dmg -> and back of. With that in mined you dont want to take gold runes. Even thou its cool and uniqe and stuff, you want dmg (ap) and armor/health runes to trade even more efficiently. Also AP and armor/health runes have an gold efficiency of like 600 gold. Thats what you get after 20 min of gold runes. So what you are doing is trading 600 gold early game for 1-600 more gold late game. Interesting but 600 gold is worth more early then late game.
Furthermore ryze scales better with AP now then with mana so going down the support tree isn't as efficient anymore. The offense tree gives you much more dmg. you could do a mix like 15/0/15 to get both the mana and ap % but 21/0/9 or 21/9/0 is probably better because of the resistance reduction %.

Oh and dorans ring gives you more dmg then crystal as a starting item with the new scaling. And helth and mana reg. So you probably want to start that if you are not rushing tear super fast.

With all that said I have actually not tried this build and have no clue. But after like seven games with the new ryze thats how I interpret how to build him.