Data, like his "brother" Lore, was created by engineer, scientist, and inventor Dr. Noonien Soong, on the planet Omicron Theta, which was stripped by the so-called "Crystalline Entity".

If you watched episodes of TNG dealing with Data's back story, you would know that the colony on Omicron Theta was not especially technically advanced.  Given that Soong's primary goal was to create a fully functional positronic neural net (Data's brain) inside a humanoid shell, and given the general lack of technology elsewhere in the colony, I would say that it was not high on Dr. Soong's priority list to give him the ability to access computers and other electronic devices by non-humanoid means.

One could ask, why did Starfleet or Geordi later augment Data to have that ability?  It was emphasized many times in TNG that most members of the Enterprise D crew consider Data to be an autonomous life form, and so they likely would frown upon such suggestions as disrespectful.  (Earning this respect was not always easy: Dr. Pulaski, case in point.)

I don't have commenting abilities yet, so let me say here I take issue with the comment by "The Spooniest" made below the original question.  Data was not "designed to function as a crew member".  He was found on Omicron Theta by Starfleet officers, and his own career in Starfleet came later.