The main benefit of having more than one person with BL/Hero/TW is that if the raid doesn't use it off the bat, its more likely someone will be alive with it should your main user die or you can have another person lust for anyone who dies and regain lost dps from them being down. I would consider BL an essential raid cooldown, not necessarily a survivability cooldown in the case of Amp magic or VE, but a raid cooldown nonetheless, as its a cooldown that benefits the entire raid.
Heroism always was a raid CD, and why not?
Before MoP it was used for this quite a few times and in a sense it is the "original raid CD", the prototype. In MoP we just had no need to use it that way (that I can remember on the top of my head).
It is a raid CD, yes. However it is a very special case. Every other raid cooldown benefits from having more. You can double up on HTT's, VEs, even chain crit banners. Lust is the one CD that has almost 0 utility in having a second user(dead people can get a second lust but even then, the CD might just be up to begin with). This is why you cannot consider it raid utility since you only need one and there is no reason to prioritize another lust user for your group if you already have one.