See I've went /whm 1-75 without someone mentioning that they wanted me to be /rdm.
Elemental DoTs were asked plenty of times to help "debuff" > DoT. Every little bit helps in a party. If a BLM doesn't do their job specific DoTs then they're not doing too well in the party, imo. Most people think a RDM or WHM suck if they don't cast slow or paralyze so it's a must for me to cast my appropriate DoTs at the start before I start nuking. 25mp for stat debuff and DoT does help more than what most people think. Race doesn't play a role on if it should be used or not. The races that don't have huge MP pool or not a whole lot of INT should still cast DoTs. 50-75MP isn't a whole lot of MP.