My theory on why this season is so rushed:
They're tired and want this to end.
Think about it, the cast and much of the crew have been at this for about 10 years. That's an eternity for TV. During that time you can't involve yourself in other projects because you're filming the series, doing press tours in support, etc. The show becomes your life. Any other acting gigs are cramed into the time left, and if those involve a prominent role in a TV show or movie...more press tours.
For 9-10 years they have labored under that schedule. While paid handsomely for their work, and make no mistake I don't begrudge them for that, they probably want to do something else. This season alone could take two full seasons, but instead we're done.
The story demands more time than everyone's willing to work. Everyone wants to move on, that's how I see it.