why 1080p is bad?

We already know how this SOC will perform at 1080p. If you check this review of the Nexus 4 (http://www.anandtech.com/show/6440/g...xus-4-review/3), and look at the GLbenchmark 1080p offscreen tests, you can see that the expected results are lower than the average. Now, add to that the clutter of the HTC sense skin and things get worst.
Moreover the battery is just too small to support so much pixels and such a heavy CPU-GPU combination.