I understand where you're coming from but i wonder if you dislike the concept of cliffhangers in general?
I understand that cliffhangers are a staple for soap operas for decades but the first one that mattered to me was back then in the original run of Star Trek Next Generation in season 3 with Best of Both Worlds (yes, i am that old

) My buddy and me nearly fell out of our chairs when we saw it and it was a discussion topic for the entire summer. We were also on a complete news embargo since back then there was no internet or Youtube where new pieces of information were posted instantly.
There was no possibilty for a Game of Thrones /Jon Snow was killed type of leak when the actor was spotted on Game of Thrones sets after his character was supposed to be dead.
Anyway.. personally i liked the cliffhanger and the suspense and had built my own theories on who would be killed. Glenn was a strong candidate since he was also killed in the comics in the same way and in the same situation and i thought it would have been a ballsy move on the side of the producers to follow the comics because Glenn / Steven Yeun was a fan favorite character (myself included) and it would have been one hell of a blow to fandom and the show to lose him.
So when the waiting was finally over and they killed off Abraham (not as much of a fan favorite but still a cool character and actor) i thought they played it safe like so many other shows who would put main characters on the chopping block in a season cliffhanger only to have them resuced at the last second when the show resumed airing.
So i liked what they did as brutal and heart wrenching as it was because it raised the stakes considerably and introduced or solidified Negan as one of the top villains of the show (if not the best) and while it was unlikely they'd kill off any more of the core group that season you couldn't be sure and that led to an interesting experience during the show.
I wonder now why you would be ok if they killed off Abraham in the season finale and in the season premiere performed the twist and killed Glenn.. why does it matter if there were a few months in between? The result is the same and the shock would be the same. Sure i would have liked for Glenn to survive and continue his story with Maggie and i was pissed and sad at the same time for a while but this elevated Negan to become truly entertaining to watch as he kept the viewers on their toes all the time (this is why i love to watch Walking Dead reaction videos and it seems people are really invested in it because if this. When Glenn was killed there were several mental breakdowns and buckets of tears to be shed.. look around for any other show that is capable of doing that with its viewers).
I'd also disagree that it would be a good thing to do what the fans would like, if they did that they'd kill off an inconsequential supporting character (like Abraham), people would discuss it for a week or two and then settle into the new season and watch it all play out back and forth. This way everytime someone pissed off Negan or gave him lip you didn't know what would happen and that was exciting (at least to me). Otherwise the show would lose appeal fast if you knew that main characters would be safe from everything which would reduce the show to the hundreds of others that put the main characters in jeopardy yet pull them out time and time again.
This is also one of the main reasons why Game of Thrones is so popular. people lost it when Sean Bean was beheaded in the first season and really lost it when the Red Wedding happened.. nobody liked to see Bean die (again

) and the other Starks were also very well liked as they were the beacons of good in a show that was full of shady or downright evil characters.