There is definitely value for Canadian customers to use the new Canadian data centre, however, for many a US-based droplet makes more sense. If the droplet is located outside of Canada and the service it provides is effectively consumed outside of Canada, then I would expect it would not be subject to Canadian GST/HST.
Digital Ocean clearly feels different as you are now charging Canadian customers GST/HST regardless of the droplet location. You must have consulted the Canadian Revenue Agency on this subject and received an Interpretation letter from them. Please post it.