If by "old titles" you mean MK2 then nobody would argue. MK2 had a presentation and immersion level that is still unmatched by most games. It took itself completely serious and swung for the fucking fences. Beyond that tho, you can't find too many people that won't say MK4, the entire mk3 family, and even MK1 were varying degree shit shows. Loud and full of shock value, maybe, but full of copy and paste, cornball ideas, and derivative designs. Like seriously, take a step back and look at the costume design for non-ninjas in mk3.
Regardless, you're forgetting the principle difference between the MK1-3(almost 4) era, and DA-vDCs era. Those first games were made on dedicated hardware and backed by the king of american arcades. They had game design carte blanche and all the resources of Midway at their disposal. DA and on were forced to work multi-plat and were less about attention getting and more about supporting Midway's financial hemmorhages. That meant smaller budgets, tighter windows, less design risks, and more pandering themes. And that's ignoring the loss of Tobias along the way.
Like the story carrying on without Tobias, I feel the sound has mostly suffered from the increasingly reduced role of Forden. De was really the first game where it became apparent he wasn't the only cook in the audio kitchen anymore, and there's next to none of his traditional style left at this point. That said, the goal of Injustice's development was to stand as far away from MK as it could, so if you really thought Superman and Batman were gonna be slugging it out to Techno Gothic beats, you were setting yourself up for disappointment.
There was actually an interesting article (I think on gamasutra) from Harada about a similar issue he's faced with the Tekken franchise. He continually gets raked over the coals for the way the sound design has "evolved" in Tekken games and he basically said "staff changes, voice changes, and tech changes. Just because you liked how it was, doesn't mean they won't want or have to change it later on. So, vote with your wallet." And since TTT2 and Injustice both proved to be sales hits, clearly not too many people minded.
