We've seen plenty of Half Orcs, in cities. Drow have walked through sword coast cities in FR, under certain circumstances. NWN had a Kobold Bard if memory serves. I see no reason a single Goblin would be barred, much less killed on sight, in Baldur's Gate, at least by officials. Now, the reaction of the general population might be different, but again, I stray goblin might not be unusual in a dock warehouse or other low end district, while they would likely be less welcome in the wealthier parts of town - though even there, I can see a well known wizard or wealthy "oddball" keeping a goblin as a "novelty" retainer or servant. And there is plenty of room for a goblin of "ill repute" working in the underbelly of the city.
A goblin PC would certainly be exposed to very different experiences than your typical Elf for certain. I could even see the Goblin character having to arrange entry to Baldur's Gate via less approved methods, and perhaps after fulfilling some incidental quests that put them on the government's radar in a positive manner, some form of "we'll officially allow you to hang and even do stuff for us, but better be on your best behavior or else" response.
Depends on whether the devs feel it is worth expending their resources on this, but a route of this kind for "outsider" type races such as goblins, kobolds, svirneblin, and so on would be fun to try - especially if given "good" and "evil" routes.
