I think it is unlikely that a 10 minute block target time is the optimal time from purely an engineering perspective. I think it is most likely that the 10 minute target time is a compromise between being able to easily explain how bitcoin works, and the optimal target block time. I would imagine that explaining that blocks are found on average, once every 9.45 minutes would probably hinder the long-term adoption of bitcoin
If you want to figure out why Satoshi chose the parameters this way and if you are asking about "why 10 minutes" then you are already asking the wrong question because "10 minute" is not an existing parameter. The parameter that exists and should be investigated is "2016 blocks in 2 weeks". So the question should be what was the significance of 2016?
The code has a parameter of recalculating the difficulty every 2016 blocks, however, the
bitcoin whitepaper specifically references blocks being found once every 10 minutes.
The significance of a 2016 block period is, in my opinion, similar to my explanation as to why the 10 minute target for blocks is 10 minutes -- I think it is likely to be a combination of engineering optimization, and to allow for bitcoin to be easily explained to a non-technical user ("bitcoin's difficulty changes approximately once every two weeks" as being a dumbed down explanation as to how frequently the difficulty is recalculated).