Rushing
seems to be a pretty deep noob trap. If you want the additional burst to your burst as an AP, Luden's is usually a better route. Ezreal can stack it pretty quick too with his cooldown reduction.
isn't really all that much scaling (50% AP + 75% base AD which will sit in the neighbourhood of 50-60 + half your AP which might be 50-75) and it doesn't really become the burst demon it's known for until it sits at about 150 AP from scaling (300 AP on champ).
are better ideas for rush, the latter for mana in this case probably-- Ezreal's bound to use up a lot.
could be fun if you ran into Manamune but generally speaking, Ezreal's relying a lot on not really getting caught in the first place with his E-- once he's pinned down these days, he's gonna have a tough time coming out of it.