In business, surprises mean that there has been a breakdown in process. Often, these situations are followed by a retrospective to figure out how they can be avoided in the future because they hurt productivity and lead to interpersonal tension. So given how we treat surprises in a professional context, culturally why do we treat surprise birthday parties as a compliment? Until the surprise, the person being honored likely feels neglected by friends and family not offering to celebrate together.
It's ironic that planning a surprise party usually entails deceiving someone you care about in ways that are typically characterized as unfriendly, which is the exact opposite of what the surprise party is intending to convey. This doesn't mean you should avoid surprise parties all together, rather it's a reminder to be thoughtful about how you go about executing them.