Plus, it makes it easier to customize your character in general.
Not that it isn't common in RPGs, but its odd that a game as story focused as EotE tries to be has such strict rules for Characteristic customization.
It's designed this way because, you can either choose a species, with certain strengths and weaknesses - you can choose to enhance the species strengths or compensate their weaknesses. There IS a species that allows for outright customization: Droids. You can do whatever you want with Droids, but that freedom has it's drawbacks as well (no force use, or normal healing).
If moving all characteristic points around freely is allowed, then why would anyone pick a Droid? Why not pick a human, which can be Force Sensitive and receive normal healing?
I think most people in this thread are okay with the "one time use" idea of doing it for only ONE characteristic and ONE point. This allows a little flexibility and isn't a re-write of a species.
A friend of mine asked me if he could start with the Droid characteristics (1 point in all attr and whatever the starting xp is), build it however he wants to spend the xp, but just say it's a Wookie.
Basically, he wanted a Wookie for RP reasons, but wanted the flexible build of a droid. I didn't let him lol.
I mentioned this earlier, in the case of Guri. The CRB even says their are droids built to look like other species, using synthskin (WTF Terminator?)