However, this strikes me as a little odd. With clones, the Emperor had a group that, like droids, could be made to somewhat mindlessly follow orders. It is one thing to order an automaton to kill . . . quite another to order the same from someone else.
But of course, human history tells us it is not terribly difficult to get soulless killing out of someone, even from a group that is initially subject to a moral code, so perhaps that was not so far a leap as I would like to think.
But in any case, post-war, with the Imperial Senate still fancying itself meaningful, it seems likely that no additional clones were ordered, and those who remained were kept in service (and as cannon fodder) as a transition occurred. New recruits would've thus seen and become used to the sort of blind allegiance we might be pondering, which would've been useful in itself.
More to the point of the title of the post, though, I would daresay that having clones about which you don't have to care (as so exemplified by members of the Republic Senate in TCW) had a dehumanizing impact. Later troopers would've been thought of with less concern than military troops of a pre-Clone Wars era, over and above a likely continued erosion of ethics under Imperial rule. That is to say, the clones served Palpatine's purpose by making the Clone Wars easy . . . later, they were no longer needed politically, and indeed it probably served his purposes better against the Rebellion to have Rebels shooting "real people".
But by the time the Senate was wiped away, there was no longer need for such considerations . . . the value of lives in a moral and political sense had been overcome by the rule of fear.