Mordin feels responsible for the still born babies that result from his work on the Genophage. Understandable, but not reason to cure the Genophage. People who champion the cure either ignore the reason the Genophage was created and ultimately used. The Krogan population exploded due to their refusal to institute population controls and began raiding other occupied worlds for resources. The Genophage was used to halt their galaxy wide slaughter.
This was not something that was done by some distant ancestors. This is just one generation out from the Krogan of ME3. Modern Krogan culture has not changed from those days. If anything, they are more aggressive. The risks are too great for blind optimism and the guilty conscience of one old Salarian to sway the decision of curing the Genophage.
As a race, the Krogan have shown no remorse for the actions of their fathers and mothers in the Rebellions. The "piles of children that never lived" is the punishment for the pile of victims their parents left in their wake on every world they attacked. It may have been a long time ago by Human, Turian, and Salarian standards, but not so long by Asari and Krogan standards.
it has been said by many that the Krogan race is going extinct due to the Genophage, but as I have said several times they are dying out because they are killing each other. The number one cause of Krogan deaths on Tuchanka is by gunshot from another Krogan. If they would focus on rebuilding their world rather that routinely attacking each other, their populations would be stable if not growing.
And Mordin should feel responsible, because he led the team on Tuchanka that released the Modified Genophage. Everything he said about "evolution" is crap, because he just contradicted himself. It would have taken hundreds or thousands of years for the Krogan to fully adapt out of the Genophage, but yet again, Salarians boot them with another Genophage.
There is an origin to a mistake, and that origin originated from the Salarians. Uplifting a race that hasn't even evolved to the point of Mass Effect Technology will come back to bite you in the ***! Yes, the Genophage was used to ensure the Krogans couldn't populate at extreme numbers and to minimize the rate in which they can replace lost Krogans within the Krogan rebellions. Eventually, the generation of Krogans during the Krogan rebellions died, obviously. But their problem eventually becomes their children's problems, and so on and so forth. Your children pay for your mistakes, and eventually they will blame those who have made their lives miserable as well. That is why Krogans don't show remorse to those that have been killed during their fathers' and mothers' days. Within every generation of the Genophage being in effect, there are less Krogans to replace the older Krogans, and yes, eventually they do go extinct from natural causes. Killing your own kind is a natural response by nature, and I am pretty sure that is apparent even to humans. When one goes desperately hungry, they kill another person who has food. Same thing applies to the Krogans, but in a different manner but same concept, they kill each other for survival and for resources because of their nuclear wars.
Tuchanka's resources aren't enough to fully stabilize situations on Tuchanka for long, they will eventually need to inhabit another world due to their world being strained of resources and consisting of bare wastelands due to Nuclear War. If they wanted to rebuild they need off-world resources.
No species is perfect in their own right, but Humans are the most diverse aliens because every individual is vastly different from one another than individuals from another species. For Krogans, they are naturally aggressive, yes, and they have yet to evolve out of it because of their long lifespans that equal Asari lifespans. Their uplifting has skipped many generations of evolution, and all of that is due to the Salarianss uplifting of the Krogan. The uplifting was the main problem, everything else is a casualty of that problem...