My Interpretation is pretty similar to some already discussed, and mentioned in part by DrT in Re-Ordered on ficwad.
Dumbledore wants either a mutal take out of Tom and Harry, have him killed by Voldemort so that he himself can kill Voldie.
Or, if Harry suvives the battle with Voldemort, having him as a replacement as the leader of the light and if Harry does not confirm to his standard having him killed.
Given the general feeling of Dumbledore the last most likely by Snape after the final battle.
If this is Dumbledores plan, the addition of Snape after he wounds himself on one Horcrux and considers himself dying before the end of the war then everything, even Snapes betrayel could be part of Dumbles plan.
We don't know if Phoenix are as light creatures as they have been portrayed, or if they simple dislike dark magics, since Dumbledore had Fawkes.
I also believe that Dumbledore bound or somehow repressed Harry's magic and either through the link with Voldemort, or the magical repression or his raising by the Dursely's Harry hides or is restricted in using his intelligence.
The Prophecy (if it is even real) said "the dark lord will mark him as his equal" not "when he himself was a baby" or "after he has trained a few decades and did a number of power boosting rituals"
That is why I think Harry recived a Riddles magical core after the killing curse struck, if he just recived little bits and pieces, why then is his wand the brother wand of Voldemort?
And Dumbledore, who knows he will one day die wanted to make sure Harry could not be a second riddle by lowering his power.
A few indicators of something beeing fishy are also there.
Harry's first corporal Patronus beeing able to take on hundred Dementors?
It seemed a little fishy.
And in the Graveyard, from what I understand Voldemort and Harry fought in some way.
And there are only three factors that I could come up with that could mean anything in this brotherwandduell. Magical Power, Skill, and knowledge with and about magic and willpower.
Voldemort is insane, at least partially, he survived 13 Years mostly on willpower, and he has not only graduated Hogwarts but also learned a lot obscure magic.
That leaves only magical power.
And if Dumbles wanted to avoid Harry having a big head, what better way (other then what he already admitted, i.e. sending him to be unloved) then to restrict his magic to the level of everyone else?