I agree with you - that said, it all depends on the situation. Good manager will present the same thing as almost mandatory to someone who is more extroverted, and as completely optional and not a big deal to someone who is not. Both of them will feel appreciated and will feel comfortable in the company, which is actually the whole idea. Some people need this kind of exposure, some don't. We just need to appreciate the fact that we are not all the same, and that we all need to have our own way to deal with the socializing rituals.