Because romancing a Twi'lek is better than romancing a Jawa.
...
Or is it?
I had to look both of those races up, and its a tough call, but Im going with the Twi'lek. Those tubules are kooky but Jawa's are creepy with those mechanical eyes.
As an aside, anyone know of a picture of a Jawa where they are disrobed and you can see what the species actually looks like? Are they robots?