Do we actually know what the reproductive rate of ancient elves was, or did I miss something? Apparently there were enough of them around that Falon'Din could kill so many that the blood would fill lakes as wide as oceans, and Elgar'nan has a million slaves working on his eidolon, from that entry in the Vir Dirthara.
Sorry, we don't know this for a fact, I'm just guessing. Generally, longer-lived species tend to reproduce less than shorter-lived ones (compare the breeding rate of elephants and greater apes to, say, rabbits and other rodents), and societies where the life expectancy and infancy survival rates are higher reproduce less than societies where the life expectancy is low and infant mortality rate is high.
And then, of course, thanks to Tolkien, it's been kind of a standard fantasy idea that elves reproduce way less than the shorter-lived races since they live longer and thus there's less need. (I believe Tolkien's elves rarely reproduce--they have one or two kids and that's about it, since the kid will theoretically keep them company until the end of the world. In D&D, elves live to be about 600-700 and retain their youth in all that time, so they tend to only have a few children at most throughout the centuries. Only the drow breed like rabbits, and that's just because of how often they backstab and murder each other. They have to keep breeding to keep up with their high, self-inflicted death toll.)
You might be onto something, though. I hadn't considered that. What if ancient elves reproduced a great deal despite being immortal, which caused huge overpopulation problems, which might have contributed to the high death toll in wars and slave sacrifices?
Or the stories of the ancients' death toll were exaggerated to make them seem greater than they were. You never know.
Which brings an interesting question - would Solas even care to have children? We don't really know how ancient elvhen families and relations were, but it could be that the role of "father" or "mother" wasn't tied to biological parents; in fact it's curious whether a lot of ancient elvhen population HAD any biological parents, given that they could just manifest from the Fade.
Um... do we know this for a fact? I know it's a popular fan theory that ancient elves were derived from Fade spirits, or Fade spirits taken physical form or something like that, but has new evidence come out to support this? 
Therefore Solas might desire to be a father-figure (he DOES like to mentor people and most of them ARE like children to him), rather than actual father.
In fact, in a way, he's a father to all of modern Thedas (which kinda brings new spin into the whole "our Maker abandoned us!") - that's a permanent imprint on reality no desire for passing on own genes can ever rival, and whatever he's planning to do next, it will leave another permanent imprint on it still.
Well, you never know. He's seen a lot and has a lot of unique stories and experiences to pass on--preferably to someone close to him rather than the masses who just worship him like a god or spit at him as a devil. Having some little Dread Wolf pups who love their daddy, who want to hear his stories, who want to be like him (you know little kids, "When I grow up, I wanna be my dad!"), and who might want to carry on his legacy would probably mean more than little kids who've been raised to either blindly worship him (as those in the past did) or hate/fear him.
It's also all but stated that Solas is very lonely. Cole mentions that when he was the Dread Wolf in Arlathan, he didn't want people to worship him because "worship makes you more; he just wanted to help." DAI also explores how being the Herald of Andraste is in some ways isolating, because people are so busy putting you on a pedestal it's very cold and lonely from up high--and Solas commiserates with you on this in Trespasser, talking about how the elves worshiping him as a god is not so different from modern Thedas worshiping you as the Herald of Andraste. Then, of course, he spent centuries wandering the Fade alone, and it's implied that he's seen many friends die over the years. After the Spirit of Wisdom is killed in "All New, Faded For Her," Solas says something like, "It never gets any easier." He's likely lived to see so many friends and colleagues die.
Even if he doesn't have children to carry on his own genes for his own death, it might be comforting to create and rejoice in new life, so he doesn't have to just dwell on lost life and those who are no longer here. (Of course, this might require Solas to stop dwelling on the past before he's ready to take that step...)
Of course, I could just be blowing all this out my ass. You never know. It's just different things to consider.