I have no objection to there being creatures in the game that are effectively "half elven" or "part elf" or "my great, great grandfather was an elf--and still is--and I guess I got a bit of that."
I do have an objection to using the "race" mechanic to model that, simply because it says "race" on the mechanic. It is already a relatively poor fit for modeling racial differences by blood as it is, but you can kind of see it for major delinations. But for "sort of elf", it is typically just a waste of space. If feats didn't conceptually remove the need for a "half-elf" race in 3E, the 4E backgrounds should have finished them off. Right now, it is running on inertia alone.
Ever heard the story of the grandmother that always cut about an inch off the roast when she cooked it. The daughter and granddaughter faithfully followed this practice, assuming it had something to do with the way the juices cooked, or the herbs got in, or something. They didn't really know. Then one day the granddaughter had the grandmother over for dinner, and fixed the fabled roast. The grandmother asked her why the ends were cut. The daughter was surprised and explained. The grandmother said, "I always cut them off because it didn't fit in the pot."
Half elves in 4E are roasts with the ends cut off for no good reason.