I don't know very much of anything about the ARKHAM ASYLUM games or the latest SUICIDE SQUAD game. I am not a gamer and I have many PS3 games in my closet that have never been loaded. However, I know that the ARKHAM series means a lot to you and I am sorry that it has disappointed you.
I did look over a plot summary of SUICIDE SQUAD: KILL THE JUSTICE LEAGUE. It is peculiar to me that the developers, Rocksteady, has made so many Batman games in their own video game continuity, the Arkhamverse, a Batman video game universe in which Batman is the lead character, only to then treat the character like a supporting player who is then killed off.
One would think that such a story could be presented in a Suicide Squad-centered continuity rather than the main Arkhamverse continuity. It is also strange to me that a licensor would make a game where the player kills the heroes, although I am hardly the final arbiter of taste.
I would note that the director of the original ARKHAM ASYLUM game, Sefton Hill, is credited as director on SUICIDE SQUAD: KILL THE JUSTICE LEAGUE but in fact left Rocksteady in December 2022 and the game was reportedly completed by others. I don't know enough about this to offer any real assessment, but it is always difficult when a creator comes up with ideas that are unconventional and but then other people without the some unconventionality are the ones to execute them.
Demoting Batman and killing him off is a choice where maybe the person who came up with the idea needs to be the one to shepherd it to completion. Maybe Hill would have carried it out more satisfyingly and compellingly. It seems like what's most upsetting to fans: this was reportedly Kevin Conroy's final performance as Batman in the games before he died. Conroy was a definitive Batman, and complaints declare that his final appearance didn't capture the appeal and enjoyment of his Batman but was instead insulting towards him.
It looks like the game will have a sequel, an additional year's worth of gameplay in downloadable content. It's entirely possible that Batman's death in the game is a temporary situation. Batman has died in the comics at least 10 times only to return via magic or time travel or Fourth World technology or voodoo or whatnot. However, even if the Arkhamverse Batman returns, Kevin Conroy (probably) won't.
I do not know enough about these video games to say whether or not Batman's death should be taken seriously; in comics, Batman's death is at most an extended coffee break.
I do not know enough about these games to say whether or not it would be upsetting if the resurrected Arkhamverse Batman were voiced by Roger Craig Smith (I read that Smith voiced the younger Arkhamverse Batman in ARKHAM ORIGINS while Conroy voiced the present day version in the other games).
DC has had some curious attitudes to licensing Batman over the years. I understand why a studio would think Zack Snyder and Batman are a great match, but then there was Batman's deeply unflattering portrayal in TITANS. That bizarre presentation of Batman as a mentally fragile figure was also crippled by Warner Bros. refusing to let Batman wear the Batsuit in the show. Batman is absent in BATWOMAN and GOTHAM KNIGHTS, but his absences make him seem either incompetent or uncaring (intentionally or not).
What's behind this? Well, to me, the whole DARK KNIGHT RETURNS storyline is one of the most abrasively insulting Batman stories ever written, and yet, it's viewed as character-defining by most Batman fans and most of DC. Maybe the Warner Bros. licensing office sees downbeat cynicism as on brand for Batman.
I would prefer that the caretakers of Batman insist that Batman be a heroic figure who, even if he is to be killed off, is given a death scene that reflects what makes Batman an iconic and powerful character. Something like flying a nuclear bomb away from the city or stopping the embodiment of evil or dying in bed after solving 15 murder mysteries based on nothing but casefiles and with his dying words bequeathing his favourite quick Bat-Disguise Kit to Alfred, his favourite Bat-Glider to Dick, his favourite Bat-Decrypter to Barbara, his favourite Batarang to Jason, his favourite Bat-Sonar Lenses to Cassandra, his favourite Bat Signal Jammer to Stephanie, his favourite Bat-Claw to Kate, and all the Bat-Computers to Tim.
There is one Batman death story that I really like but still find questionable: LAST KNIGHT ON EARTH. Spoiler warning: it features Bruce Wayne waking up to find that Earth is a post-apocalyptic wasteland ruled by a supervillain named Omega who killed all the other heroes and villains. Bruce is baffled by how he has no memory of how the world came to be in this state and in addition, he notices that even though he should be in his 70s given the span of time, he is somehow in his early 30s. Bruce seeks to unravel the mystery of the past while evading the ruling supervillain of this world, Omega.
Bruce comes to a disturbing revelation: he isn't Bruce Wayne at all. He is a clone, a backup plan established by the original Bruce who wanted to ensure that upon his death, a cloned replacement with all the training would take over as Batman. Bruce is further horrified to learn that the original Bruce Wayne survived the supervillain war by becoming Omega and has become embittered, twisted and ruthless. The ending has Bruce defeating Omega and beginning the work of rebuilding the world, hoping to carry on all that was good in Bruce Wayne while leaving behind the bad.
I am not sure I like the idea of Batman becoming a supervillain who is defeated by his clone, but LAST KNIGHT ON EARTH is still engaging with what it means to be Batman and declares that Batman is such a planner that he would, deliberately or not, plan for his own defeat should he ever become a supervillain. In contrast, Batman's demise in the Arkhamverse, based on a summary, doesn't seem to really tap into what makes Batman special.
However, I have never and will probably never play the game, so I can't claim to have any real opinion of it beyond saying it sounds like a strange choice.