See, this is an aspect of the current game rules that I really dislike -- in many ways it shows me why 3.whatever was better for my tastes.
Under the previous rules, there were hordes of options for a character, even with simply the PHB in hand. You could multiclass, mix up your class, and be whatever you wanted without having to wait for a whole new class to be created (which I felt was a major limiting factor with earlier editions of D&D); now, we have gone back to the pre-3e problems.
Sure, we will eventually have a swordmage and other such classes, but the image here is of slotting -- Tab A into Slot B, without variance. Players and GMs are to accept pre-determined, limited paths rather than allowing wider variances. Once you choose a path, you are pretty much limited to that path -- anything you do to mix things up very, very quickly becomes, to say the least, sub-optimal.
3e was all about choices; 4e is about making a decision at the beginning of your character's career and then limiting what you can do with that after the fact.