Shooting my shot, should my enemies be able to do the same?

The final genre that I was tasked with adding into Super Powerful Death Fist was the shoot 'em up genre. 

Of course one of the core elements to a shoot 'em up is well... Shooting. So of course I made it so that later on in the game, the player would have the ability to shoot projectiles towards enemies. 

So now that the player was able to shoot, I thought I would save myself time and just keep it at that. However, something felt off about it. 

Now that the player could use ranged attacks, the melee only enemies didn't stand much of a chance against him. To combat this I initially just tried making faster enemies with less stun time. The idea being that they would close the distance faster than the player was able to shoot them, but it still in general felt very off. 

Because of this I decided to cut my losses and add an enemy that was able to shoot just like the player could. 

This new enemy type was given a different shape in its design compare to the other enemies so that the player could immediately recognize that it did something different, and was given less health so that players could dispatch of them quickly.