have u checked out my post?
im not sure now what chapter it was, but madara has a laboratory full of uchiha eyes and i also think he did not bring up the effort to select the worthless eyes. So if Kabuto would simply use the DNA from those eyes, he could bring back a lot more strong Uchihas
Sorry, I didn't check your post.
Madara has that yes, but does Kabuto have access to that lab? I can't remember if he has.
And generally, Sharingan eyes are not worthless. But regular Sharingan bearers don't present the same kind of danger that a Mangekyou Sharingan or EMS eyes present.
In the history of the Uchihas, there haven't been that many really powerful Uchihas like Madara and Itachi. Most members just developed the regular Sharingan (if they already developed that) and that was it. Only a few went to the next stages of them.
So when raging war, it's better to bring back those select few that are really powerful like Madara and Itachi, then bring back a whole clan with just the regular Sharingan.