I know this is how people in the 80s and 90 imagined the future and a lot of concepts were probably too far fetched for them.
BUT... why arent they using drones to explore planets? why are there not more drone-spaceships? why does enterprise need a crew to begin with? Why is there so little automation? Why so few uses of AI in general?
I am saying this as a star trek the next generation person. I'd also expect them to have full video and sensory streams of any surface mission teams.
Having also recently seen that episode, they send Data in because he's the only one who wasn't confused by the time weirdness. Picard even tells him sending others would only slow Data down and if they should get hurt it would make the time sensitive mission even more difficult.
As for why they don't have more Datas: They don't even know how he works. The dude who made him and Lore died without sharing his research.
Oh I didn't get that far, I do remember Data's whole exploring his roots/dad episode from back in the 90s when I watched at the time. But haven't gotten that far in rewatches yet. That would explain why they can't back him up to hdd. They probably wouldn't get all the permissions for all the folders right so a restore from backup would probably not work.
Actually... That kind of backup may be possible... 🤔
I mean, if they can accidentally backup real humans (second Riker, Scotty in the transport buffer, Broccoli turning himself into a super computer, etc), surely they could purposely backup the android. lol
The one time they purposely "backed up" a human via the transporter it took up so much space they had to dump the backup into the holosuite and it still nearly brought the entire station's computer to its knees.
To be fair, that was Cardassian technology. Maybe the Federation's stuff is better.