I worked in food service once in Bonaire and learned, it's always good to tip cash. If you do not, some establishments deduct a fee from the tip due to CC transactions. Also, if you are from the US, please tip as you would back home. Folks rely on these tips. As do dive masters, taxis, housekeepers, windsurf instructors and valets/concierges.
Do you have any estimate of what percentage of visitors are from the US and what percentage from Europe, particularly the Netherlands? There is no way someone from the Netherlands is going to leave a tip. (I don't mean to pick on the Dutch. Although Bonaire sees lots of Dutch visitors, due to the island's status, there are plenty of visitors from other European countries that have no tipping culture. A Belgian isn't going to tip, either.) When my wife and I are sitting in a restaurant, and the Dutch couple next to us leaves no tip, are we Americans expected to subsidize the server because others do not tip?
The service charge resolves this whole quandary of tipping in international tourist locations where not everyone is American, and I would hope most establishments see the benefit.