I don't think it's so much of an issue of feeling left out as it is feeling pressured to suffer through it with a smile on your face.
Being visibly unhappy or disinterested while you are there usually brings additional pressure to engage. Leaving early invites later questions that require you to lie to be socially acceptable. And if the events are frequent enough it'll be obvious you are lying sooner rather than later.
And then add in considerations about what those above you in the company will think.
It's enough that I do have similar responses to such things. And it's also true that it's probably a somewhat too extreme of a response. Thinking about it is usually worse than actually being there, as it's usually possible to end up off in a corner with one or two other like-minded people which is mostly tolerable.
Although as things get more structured this gets harder, and the structure is usually accompanied by even more "optimistic language" so... again, the response seems fairly justified without invoking a need for "deep issues."