My bootstrapped startup is not consumer focused, so having a large local population is not key. But working with corporates, it's a bliss being based here. There are hundreds of multinational companies, of which many base their (edit: regional) headquarters here. It's so easy for us to reach to potential customers, and from there, to expand to other regional and global offices of these multinational companies.
Hiring can be an issue, but it's not difficult to get work passes for skilled foreigners here. Yes, there are quotas for companies hiring foreigners, but these are largely for less skilled foreigners. Many foreigners study in local universities like NUS and in turn have a bond to work in Singapore after they graduate. If you have a degree from a good, recognised university, it's not difficult to get an employment pass here.