Humans are actually very good at recognizing facial expressions and body language.
While it's true that large numbers of people are terrible at it, it's only in comparison to the average human. Assuming unimpaired vision and intelligence, humans use facial expressions to tell who among a group of people is talking, what or whom the person is referring to (because of their gaze)...at least a good guess, and many other things.
Maybe you don't know if someone is slightly annoyed vs upset, or maybe you can't tell if someone is joking, but that's as much word-choice and tone of voice as it is facial expressions. The number of things that people pick up from other people, or from animals, is much larger than you might think. If you're not sure of that, talk to someone who is blind. Or compare conversations on the phone or online with in-person ones.
Another way to look at facial expressions is as a subset of the larger set of non-verbal communication of body language and signaling.
From Turn Signals Are the Facial Expressions of Automobiles by Donald Norman.
Social cooperation requires signals, ways of letting others know one's
actions and intentions. Moreover, it is useful to know reactions to
actions: how do others perceive them? The most powerful method of
signaling, of course, is through language. Emotions, especially the
outward signaling of emotions, play equally important roles. Emotional
and facial expressions are simple signal systems that allow us to
communicate to others our own internal states. In fact, emotions can
act as a communication medium within an individual, helping bridge the
gap between internal, subconscious states and conscious ones.
As I study the interaction of people with technology, I am not happy
with what I see. In some sense, you might say, my goal is to socialize
technology. Right now, technology lacks social graces. The machine
sits there, placid, demanding. It tends to interact only in order to
demand attention, not to communicate, not to interact gracefully.
People and social animals have evolved a wide range of signaling
systems, the better to make their interactions pleasant and
productive. One way to understand the deficiencies of today's
technologies and to see how they might improve is to examine the route
that natural evolution has taken. You know the old saying that history
repeats itself, that those that who fail to study the lessons of
history are doomed to repeat its failures? Well, I think the analogous
statement applies to evolution and technology: those who are unaware
of the lessons of biological evolution are doomed to repeat its
So, yes, robots need facial expressions. They need external signals in addition to spoken or written or signed language. But they don't have to mimic human expressions. You're right that it is jarring to see fake expressions. If done right, however, they wouldn't be fake, they'd just be specific to a robot. If they are just different enough that they're obviously not human, but not so different that you can't pick up on them right away, you've hit the sweet spot.