1) Generates a lot of publicity through social media (you're posting this...) and "traditional" channels (i.e. word of mouth).

2) Opportunity to work out the kinks on an initial cohort of low-expectation customers. Openings are high-stress for hotels and restaurants, everything you could never have imagined goes wrong, and there's no way to prep for going live until you do so. By setting the bar so low you're getting that initial group through the doors with a much lower likelihood of negative feedback (Who is going to say they didn't get their money's worth?).

EDIT: What poster above said in fewer words.