Before I delete the emulator files, I'll post these here:
I did an experiement on my offline pre renewal server, to see how the classes would react if the skills had cooldown on them. Based on my testing, that would make the game require more multiplayer gameplay, and less potion chugging. I were unable to test deeper this because... Well... I were playing alone, so the skills were being kind of a hinderance for my gameplay. But I have to say, It made the classes felt more complementary, even more the Mage class.
I were only able to add actual cooldowns to the first class skills, If you're interessed in trying, you can simply copy the cooldown of the skills bellow to your db/(your server type)/skill_db.txt file (cooldown in miliseconds, you may copy right away the value). Be sure to backup the file first.
MG_LIGHTNINGBOLT: 4000 //Probably better to set to 12000, like Firebolt and Coldbolt
MG_THUNDERSTORM: 12000 //Maybe 18000?
Some of those cooldown values may not be good for gameplay in group, so you may try readjusting them. Just keep on mind that the skills have to be useful, but not extremelly dependable, when readjusting the cooldown values.