RIP indeed! Two things about him, Filmation and TAS:
First, whatever the artistic limitations, Scheimer gave Fontana and Roddenberry complete creative control. Other studios would have given us youngster Kirk and Spock at the Academy, and/or wacky sidekicks.
Second, in reading interviews with Scheimer, it's very clear that he just plain got a hell of a kick out of doing TAS. He was so excited the few times he was able to assemble the entire cast for voice work. He couldn't resist doing a few voices himself.
One more thing: Trek on a budget? TAS sure was. But it was produced entirely in the U.S. by union animators. These days all the real animation work is shipped overseas.