Joel dying brutally isnt the problem and is the proper way for him to go considering the series.
The problem is having to control his killer right after.
This wouldn't be so bad if Abby was the protagonist from the start and killing Joel happens halfway through the game after you've built a connection with Abby and understand her reason for revenge. Then they could have switched to ellie and have you kill Abby at the end. That would have been a much more emotional conclusion since you had time to connect with both characters.
The entire story would work better if they flipped the roles of abby and ellie.
Abby should have been advertised as the main character from the jump with no clue of joel and ellie being in the game and then taking control of ellie halfway through to kill abby should have been the twist.
I think them butchering the game in development due to bad employee practices/tornover forced this bad execution. This could of work phenomenally with 3 playable character. Joel, Abby, and Ellie that just switch throughout the game. Push Joel's death further down the game and Abby being chasing down by Ellie for the last hour minute of the game. Abby never finding out what Fireflies was really doing to innocent immune have to arise after Joel's death.
Everything felt sooo rushed. This plot can really work. Playing Abby after killing Joel can work. Yet, they completely fukked it all up in executing it.
Start the game as Abby and enrich her back story
Jump to Ellie and lay the foundation of the revenge storyline
Then Jump to Joel doing his thing and layering another theme of the cycle of violence
Go back to Ellie with last minute Joel bonding and revealing the truth of what happened with the Fireflies
You get the meeting of Abby, Joel, and Ellie with Joel's death
Ellie "Cycle of revenge" cutscene / A simple Joel flashblack level
Return to Abby in a state of surrealism and finding the truth of what really happened at the hospital and being relentlessly chased down by Ellie
Game ends with a boss battle and Abby breaking the cycle by not killing Ellie and telling that Joel did the right thing.
That's the importance of refining an idea instead of forcing something without proper highs and lows