Come to think of it, in hindsight I suppose, from a semi-pro-life-ish standpoint (not opening that can of worms again, though referencing it still); at least the lives lost weren't in vain, and some efficiency in their loss was at least put to a better use; however, what a waste for the others unused. Yes, I am aware of the conflict of interest from my past statement. I'm not happy about the losses in general (naturally), but at least, if those lives were going be thrown away anyhow, what has been salvaged in the process got put to some use (just as long as it was ethically done, and not a forced option (e.g. A moster orders fresh fetuses for this, and no alternatives; exaggerated as it sounds)), and justifies much of the beginning of stem cell research that used them. I suppose that justifies a great deal of it overall. I still don't feel great about it, but at least I'm not as hostile about it as previously (that was quick).
From a different angle, I just hope, if you believe in ghosts/spirits/etc., the souls of the lost can think the same way and find some level of forgiveness for it (after all, it seems they didn't have much choice from their end); despite having been denied a proper cohesive mortal existence, which I suppose they thought were promised. However, if spirits retain some form of humanity regardless of shape or form, then much like any other human being or creature, they'd still be pretty pissed off about the whole thing overall (imagine being cancelled from existence; especially before you technically exist. Wouldn't you be pissed off about that?). Of course, at the same level, others would rationalize, just as I did, to at least find some solace that there wasn't waste, or for being a life cancelled, it was for a better use eventually; being a cost of one (or few) for many upon many and not cancelled due to population control, being the result of a poor choice, or an unwilling existence (existence caused by rape, for example), or ethnic cleansing especially. If the first or last were the case, I can understand any hostility they would express; I would feel the same as an Existing witnessing or hearing about it.
As for the others not so lucky to be useful, they have made for an interesting thought experiment, personally, that made me come up with a good nightmare fuel-based spiritual race good for use in a story or game. So to put it, their form looks like a mature version of their cancelled existence if they were to continue living post-abortion (however, they still carry on as spirits, trying to make life out of nothing; unsuccessful, they become irrational and extremely dangerous and violent); in many cases, especially if not given chances to learn as a person (fresh souls with no reincarnation experience), they are also feral lost souls just trying to eek out an existence from nothing, and extremely common, aren't even self-aware (I would imagine, they're much worse to deal with than Satan himself or the Antichrist (at least they're intelligent)), and have no idea how to properly exist in general, and eat anything in sight (souls, good or bad, mortal being, and so on, even each other; and they can't tell corruption from goodness, since they've never had a chance for anything and are like humanoid amoebas). That makes for some horrifying imagery. That's how I would imagine a lost soul would actually look like. Now, let's count the numbers (again, based on when you consider life's beginning (see above post))... Holy crap. Worse off, despite their form, I doubt they're demons, even though you won't be able to tell the difference as well anyway, especially if you piss(ed) one off, or were responsible for rendering them that way in the first place (and they recognize you).
EDIT:
If that idea were a reality, I pray not only for the souls screwed out of existence (an interesting way of phrasing that), but those that made the decision, as well as those that executed the abortion.
EDIT EDIT:
@Mrhappyface: Yeah. It still disturbs me to the core. I'm too much of a bleeding heart, it seems.
EDIT EDIT EDIT:
I guess the closest thing I can think of that can explain feral lost souls would be:
Those artificial soldiers from
[REDACTED] near the end.