None of the networks provide feeds at 1080p.
Additionally, 1080i is just as good as 1080p once you deinterlace it -- a 1080i59.94 signal deinterlaces into a 1080p29.97 signal. Most TV content is only 23.976 or 29.97 FPS.
You'd be better off requesting that Dish Network stop molesting the original feeds they receive. The biggest thing that causes the poor picture quality with the cable companies and the satellite resellers like Dish / DirecTV is when they take the source feed from C-band and re-encode it before passing it on to you. If they switched to 1080p you would not notice any quality improvement as long as they keep in place their policy of re-encoding these source feeds instead of just passing them on to their subscribers untouched.
They don't even necessarily have to drop the bitrate by much for there to be huge quality loss. The simple fact that they are doing a lossy -> lossy video re-encode causes considerable quality loss. But they do also usually cut the bitrate by quite a bit when they re-encode it which further exacerbates the loss in quality.
Most of the TV channels distributed on C-band look almost as good as Blu-ray, but by the time they make it through the man in the middle and you finally see the channel, so much quality has been lost from the original feed.