Injustice single-player is all about the defense and multi-player is all about the offense. In single-player, it is a viable tactic to let the enemy hit you in the face since getting hit generates more power for your specials than attacking. To some extent it is a balance, trying to build up your charge to do more damage while making sure to block any specials the enemy unleashes on you. Multi-player is more of a dance where you attempt to constantly execute combos in a desperate bid to build up power fast enough to take out your opponent.
MKX is all offense all the time.
Getting hit doesn’t build up much power whether you are in Faction Wars or Battle Mode. However, the enemy hitting you generates a lot of power for them. So the incentive is to go on the offensive as often as possible. This can lead to some confusion when you hit fights in Battle Mode like Reptile where you suddenly have to adopt defensive tactics.
Is this better of worse? For me it is better because I’m all about the offense and the more turtle like style almost demanded by Injustice at times can be a challenge for me to adopt. I like how MKX is more tilted towards attacking than blocking. Which isn’t to say learning defense is unnecessary, it still is. You just don’t have to spend most of your fights getting punched in the face (or elsewhere).