Quote from PhanxHaving the library share your data with others even if you aren't using the data shared by others is the whole point of LibHealComm. The resources used by the library are so insignificant that there is no way it could have a noticable impact on the performance of any machine capable of playing WoW even on minimum settings.
The only possible reason I can think of to install it and then disable it is to be a douche and annoy the other healers in your group. Especially now that nearly every unit frame addon in existence supports LibHealComm, healers come to rely on being able to see at least who is being healed, and it's extremely annoying to be grouped with someone who doesn't have the library.
If you don't want users of your addon sharing their heal data with their group, don't embed LibHealComm, and tell them if they want to see heals from other people they have to install the library separately. I doubt many of them will thank you for it. Are there really users who complain about having LibHealComm sending comms and actually have some factual basis for their complaints, rather than just vague whining from a position of total ignorance?
I know this is a fairly old post to reply to, but an [admittedly cursory] look didn't turn up one point, which is that while the ideal of having LHC function whether the user running it wants to use its information or not is laudable, in reality a lot of people are using LHC when they have no business using it at all - there are a ton of raid frames and unit frames that embed it, and the majority of players using these are not healers. They transmit nothing of value, and other than a handful of people (some raid leaders, some good tanks) do nothing useful with received values either, even if their raid frames/unit frames are displaying incoming heals.
All of my raiding characters are DPS - I will never hold off using a healthstone because I see an incoming heal on myself. The addons I use should most certainly provide an option to at least unregister from incoming LHC events. Sure, you can argue that in the grand scheme of things, processing LHC messages isn't much of a performance hit, but the point is that for likely the majority of people currently running LHC, it's an unnecessary operation. I could run a mod that counts the number of times I strafe left each week at no noticeable performance cost too, but that has no value to me, so if some mod I downloaded had an embedded library to do so, I would want to disable it. The addons I use that include LHC fortunately do contain options to disable display of incoming heals (although they're vague enough in their wording that I don't know if they just hide the display or actually unregister the events) - authors of addons that aren't guaranteed to be used ONLY by people who actually want to see incoming heals or actually have outgoing heals should continue to provide options to disable use of LHC by non-healers.