If the issue is related to you intending for your character to already know the language, there is the option to start with a different language than English as primary (and you spend UE to learn English instead, though this path isn't optimal for completely new players), as well as the chargen boost in a 2nd language for sufficiently intelligent characters. If this isn't about those sorts of issue, then read on.
The language system creates communication barriers in the game. Two (or more) people who share a language can converse freely in it, and perhaps rudely, in front of people who don't speak it, much like in real life. An immigrant who doesn't speak any language you know will be more difficult to communicate with in person, sometimes to a frustrating degree, forcing you to rely more heavily on body language and gestures.
If languages were quick and easy to learn, these sorts of things would become completely moot, as everyone would go spend a few spare UE points to learn all the languages and never be kept out of the loop if someone was speaking a different language. Another key thing to understand is that SD, at least for stats/skills, is more about slow progression based on longer-term planning. You don't wake up one day and decide this weekend I'll become fluent in Simlish or whatever, you have to dedicate yourself to learning it, much like becoming thoroughly proficient at any other kind of skill.
I've had many quite wonderful RP moments where not sharing a common language, or deliberately using a language some people present don't understand, have greatly enhanced the situation. If it wasn't so difficult to learn new languages, these sorts of things wouldn't be possible.