A possible explanation on the limit
Upon browsing the Core Rulebook, Humans have the ability to learn any language with Intelligence Bonus points ( other than “ secret ” languages ). surprisingly, Half-Elves besides have this ability. To my mind, this is the developers trying to make humans more appealing than non-humans.. Maybe it is precisely the groups I have participated in but the number of humans on one hand … and I have played in D & D groups for about 20 years. however, that purely-crunch reason breaks submersion, there in truth should be a reason in the game ‘s fiction/mythology. While I believe there is no canonic explanation on this ( why justify the game ‘s reason for letting fighters swing swords ? ) under is my suggestion for an “ in-character ” reasoning why non-human lyric choices are dictated/limited until they are in play and necessitate to spend skill-points to learn whatever they want .
I see this as the languages a character learns in their family growing up. I am friends with a few families that emigrated “ here ” from a nation that speaks a different terminology. They consider it to be one of their parental duties to make sure that their kids can speak the native language in addition to the local one. They frequently justify it as “ raising a dependable [ ethnicity ] kid ” .
In Riddleport, or any early racially diverse city, your personal computer is probable to grow up learning Common ( the human terminology ? the language of occupation ? ), and the racial linguistic process … because your quality ‘s parents want your character to be a “ full ” elf/dwarf/whatever. Your personal computer is besides probable to grow up celebrating [ subspecies ] holidays and doing [ subspecies ] cultural ritual/ceremonies. Hence the other racial traits that “ all ” dwarves/elves etc. know.
When you pick your bonus languages, it is something that your character learns when they are getting trained to do their class ( whether through formal means or in the school of arduous knocks ). An archeologist is much more likely to stumble across/need to know how to read/write Cunieform than a computer programmer is. An Elf Wizard is much more likely to stumble across Draconic than an Elf Fighter. Sure, as a computer programmer I can on a caprice decide I want to learn to read/write Cunieform, but I would need to spend “ skill points ” on it rather of increasing my “ skill points ” in programming/debugging/database administration/etc .
Know when to break the rules
But like other answers have suggested, Marquee NPCs, PCs, and early edge cases exist. possibly in a racially-integrated city, a Dwarven Wizard trainee can only find an elfin Wizard uncoerced to take him on as an Apprentice. possibly that Elf Wizard swears at the dwarf in elfin when the dwarf messes up. I would rule that the dwarf could learn elfin as an “ extra ” language .
I would besides require a good backstory to explain any deviation from the “ normal ” languages/abilities .