I just wonder if some of the creative decisions might have been different if the show had been taken more seriously.
And that's because you're making the ad hoc, unexamined assumption that they didn't
take the show seriously. You don't know that's the case, you're just assuming. And it's an insulting accusation to level against the creators. It's a valid thing to criticize a work, but when you start making assumptions about the motivations and feelings of the people
who made the work, that crosses the line into ad hominem argument and becomes a petty personal attack rather than a fair criticism of a work.
But then everything is undermined by the creative decision to make the Spock and Keniclius clones WAY oversized. Except for the limited animation style you had a first-rate story worthy of TOS and then you turn it into kiddie fare with fifty foot clones.
Is it any more "kiddie fare" than Apollo growing to giant size in "Who Mourns for Adonais?" Or manifesting a giant hand in space to grab the Enterprise
? What about the giant cat stalking the crew in "Catspaw"?
Your reasoning is circular. Because of your preconception that TAS was aimed at children, you're looking at things that have direct equivalents in TOS itself and reading them as "childish" when you would not read them the same way in the context of TOS. Presumably the TAS creators did these things for the same reason the TOS creators did similar things: because they thought it would be visually interesting and science-fictional. You can also find giant and miniaturization effects in episodes of The Twilight Zone
, the least "childish" SF show of the entire '60s.