Inconsistency

I was watching an episode of Voyager last night, the one where the doctor’s program was found and activated by a Kyrian scientist some 7 centuries after they’d come across that planet, in a museum dedicated to Voyager, but in their view of history Janeway and crew were the bad guys, Chakotay’s tattoo pretty much covered his whole face, Harry Kim got to brutally beat the shit out of a detainee and Janeway was like a pirate queen (but actually kind of sexy in that role). Anyway, the thing that bothered me, that didn’t make sense, is that if the doctor is alive and well on an obscure planet in the Delta quadrant 700 years post Voyager, how is it that in all the other episodes, he continues with Voyager to Earth?
I suppose there are possible explanations, apparently he did not have the mobile emitter on him, and they can always re-activate the original program, minus the opera and stuff, but they didn’t explain it and that was sloppy, and it raises another question. As effective as the doctor was (he saved the ship more than once, and even served as Emergency Command Hologram in at least one instance) why wasn’t he ever duplicated? Couldn’t every star ship have used 3 or 4 with his abilities?
Same with Data on TNG. When you’ve got an android crew member whose knowledge is endless, whose reaction time is instantaneous, and whose strength is superhuman, wouldn’t it make more sense to manufacture millions of them, put them in command of their own ships, and send THEM out to explore the Galaxy? Some humans could go along for the ride, of course, because the whole point of exploring space is so that humans can explore space, but as far as piloting the ships is concerned, why would you ever want to go with less than the best?
I believe it was Carl Sagan who said that first contact was likely to be our machines talking to their machines. And I’m O.K. with that. The human crew just makes it more relatable to a T.V. audience.
And perpetuates that myth, which humans cling to, that we are somehow important.