Which is fine as a houserule. But if you go by RAW they shouldn't be starting out with anything they don't purchase with the starting credits. To keep all the beginning characters balanced, the astromech would need to purchase the toolkit for 350 credits to begin play with all their built in components in working order. Astromechs that don't purchase the toolkit can be thought of as having the standard factory installed bits either broken or replaced with the other items the player chose to purchase.
To me, saying that astromechs start the game as not being astromechs (not having access to their basic physiological characteristics) is like saying that rodians don't get their suction cups, or that trandoshans have to purchase headgear to see in the infrared spectrum. It's ridiculous.
Does the Rodian suction cups add a mechanical benefit to the game? If so, they should be balanced by some sort of XP cost. I am afb at the moment, so remind me... is the Trandoshan IR sight in the benefits given to PCs or is it simply fluff?