One of the clear differences between the fighting style of MK and Injustice is scale. The Injustice games feature stages that are far bigger than their counterparts in the MK games. The reason for this is to create the impression of an epic battle between superheroes, and while it certainly does this, it also comes with a host of problems.
One of these issues is that it leads to a heavy amount of zoning when you head online to play. And this, naturally, leads to a lot of frustration. It isn't helped by NetherRealm seemingly having an obsession with characters that can zone out opponents.
The offender in Injustice 2 was Deadshot, who seemed to have his entire playstyle designed to annoy the hell out of the opposing player.
For Injustice 3, it would be great to see NetherRealm to take a step back from zoning characters, and instead focus on fighters that can compete up close. We always need to have one zoner on the roster to balance things out, but for Injustice 3, perhaps they should give that character some tools for up close, so zoning isn't their only option.