The Lalafell bots are actually a hold-over from when they were optimal for BLM due to getting an extra cast before they had to switch to Umbral Ice thanks to racial stats (Though the normalized MP pools have made that irrelevant).

There seems to be two distinct groups of gil farmers; one that uses Lalafell BLM/WHM and another that uses Hyur BRD/WHM. I've also noticed the latter group tends to go cross-world when leveling/farming...again for reasons I haven't the foggiest clue about. Why they'd go to an already crowded server like Cactuar instead of a lower population where they're less likely be noticed is anyone's guess.