With the kind of artstyles I tend to use, I don't have a whole lot of experience with face wrinkles...like, this is about as extreme as my expressions get:
The wrinkles are smartly placed, yes, but there's still only two of them (the ones on her cheek don't count; they are a facial feature).
However, I think the main reason people are afraid that they'll make characters look "ugly" is because a lot of the time they do...when you don't know how to use them yet. ^^; And they are hard to learn; faces in particular have a sharp learning curve once you realize that they are dynamic, elastic forms, not static ones. And many, MANY artists spend the majority of their time viewing faces as static, because when you're drawing pinups of pretty boys/girls that's really all you need.
So obviously just introducing wrinkles disrupts that 'prettiness', and that's where a lot of artists stop and turn back. ^^; But if you're willing to move past that and try to master this skill...that's when the real hell begins...
You drew the wrinkles too big? Congrats, your character just aged 50 years.
You drew too many wrinkles? Congrats, your character just aged 90 years.
You're not completely sure where the wrinkles should go? Congrats, now your character looks like they have worms under their skin.
You drew a wrinkle 0.2cm out of place? Congrats, now your character looks confused instead of angry. Try again...and again...and again...
I think it's a little easier when you come from an anime background though, because a lot of common anime expressions require face wrinkles, regardless of art style. Like this classic 'strained smile':
Even in a chibi drawing, you need that little wrinkle next to the mouth, or it's just not the same thing. ^^ A lot of expressions are like that...and although the wrinkles are tiny and easy to ignore, they can both ease you into the concept of using them and begin to teach you where they need to go.