To be fair, BLM was harder back then. You want to keep Eno going as often as possible since its not only a direct damage buff, but it gives you access to your strongest spells. To keep it running now you need to keep either your fire or ice stance up. Thats it, just dont drop your stance. Switching is fine, just dont let the 15 second stance timer run down to 0 without refreshing it. Back then you needed to keep your stance timer going(and it was shorter... either 10 or 12 seconds if i remember right), but you also needed to cast Blizzard 4 to refresh the Eno timer - and every time you cast B4 to put time back on the clock, you got 5 less seconds. In a longer boss fight you would(ideally) keep it up long enough for the Eno recast to clear, then when the re-applied time got down to 15 or 10 seconds you would redo Eno to get it back up to the 30 it started at. In those longer fights, the beginning of the cycle would be kinda chill because you(generally) had a lot of time to do everything. Then as you went through your rotation and the timers started getting shorter it would feel more frantic and stressful. Do i have time to finish this rotation, or do i need to clip and refresh early? Oh god, why is that AoE on me when i need to get this spell off so badly? Then if you pushed hard enough, you got to the recast and things were calm again for a little bit.
But yeah, as the others said its a fairly easy class to learn. The AoE rotation is only 4 spells. Single target is 8 but with 2 distinct phases you treat differently. Add a couple abilities for movement tech, a couple buffs to manage(and a couple worthless spells we dont talk about except to complain), and thats the whole class. Mastery is where the difficulty lies. I would imagine even just doing the level 50 Fire 1 rotation i could out damage some classes, so your extra lazy guy was a real piece of work. Giving all us firestarters a bad name.