HBO reportedly offered them a pay rise and money for more seasons but D&D said they could finish the story in 13 episodes. I think we can all agree that they were wrong and season 7 and 8 needed to have 10 episodes each.
Unfortunately for us D&D have rushed the ending to the biggest show on TV so they can run off and make some shitty Star Wars movies that nobody wants.
SW is already ruined, so they won't be getting any shit from anyone about it. Because they ruined GoT and lots of people are shitting on them. It's the smart move, like it or not.
Btw, I don't think they didn't have the time, because, if they skipped a whole year to do the last season, they must've thought they'd make it better. The reason is not having the source material Martin has written. They executed his story just fine, but they can't do they own.
Btw, only for books: If they ever are done, (in which I don't believe anymore), we at least know that Aegon is really fake, or, if not fake, a catalyst for other characters in the story, Dany will get crazy, Jon will rise from death, Cersei and Jaime are going to die together. I think that George told all this is his way of ending to the show creators, and they did what they did with it.
Still I predict, just like before this season: Jon is king of Westeros, but rules from Winterfell. For the rest, have no clue.