The story finally ends, in a suitably anticlimactic manner. It feels like the folks at Kyoto Animation are as sick of it as we are.
So why did they do it this way? I suspect that the real reason, regardless of the rationalizations they may have come up with, is that the production company ordered N episodes and they only had enough source material for N – 7. KyoAni has a lot of talent, including some of the world’s best animators, but coming up with new story ideas is not their forte.
Incidentally, the ending provides the strongest evidence so far for what I called “Theory 4” in my Spoiler Notes for Haruhi Suzumiya.