Every character should have his/her own special strenght and weakness. IMO that is what makes Fighting games realistic. In life everyone is good at certain things and bad at others. There are many ways you could use this in MK.

Let's take Special moves for instance:

Fire
Ice

Now lets say Sub-zero freezes Scorpion, couldn't Scorpion simply melt the ice away? This would definately give Scorpion an advantage over Sub-Zero. This would mean that Sub-Zero would have to find a different way to defeat Scorpion. He could use his sword, but that could easily be melted down aswell. So he has no other option than to use his fighting abilities to defeat Scorpion.

Robot
Electricity

Now we know the reaction if a robot gets electricuted right? It does not effect a robot, and may even make it stronger in certain cases. So if Raiden or Asrah were to use their lighting attacks on Sektor, this should not cause any damage, and may even make him stronger and increase his attack damage. This would deffinately give Sektor an advantage over Asrah or Raiden. This would mean they would have to use their fighting skills and/or their weapons.

Knight
Weapon

Now we all know how hard it is to penetrate a knight's armor. So why should we be able to penetrate Hotaru's body armor? This would leave Hotaru with a major advantage against all weapons. Forcing his opponents to use their fighting styles and special attacks.

Knight
Electricity

It is a known fact that metal conducts electricity. When Asrah or Raiden use their lighting attacks on Hotaru he should get hurt more than usual because his metal not only would conduct the electricity, and also heat up after being struck. This should give Asrah and Raiden a very good advantage over Hotaru.

Telenetic
All others

Since Ermac and Kenshi use telenetic powers, they can attck from a good distance away from their oponent. This can help decrease the chance of being hit while attempting to use their special attacks on their opponent.

Old Fighters
New Fighters

Old fighters should be a lot smoother and a lot stronger at fighting. They have been in the tournament for many years and should already know the basics and how to defeat their opponents. This means they would have an advantage over the newcomers.

I think it would be alot more useful and realistic if MK:D would use these advantage points. It would make you think about how you could deafeat your oponent instead of the usual ways with the other fighters. Every fighter should have his/her own advantage weither it be speed or stranght or offense or defense.