A form of exposure suit will always be recommended in order to protect the coral from you. Wear at least a rashie.
The water in Bonaire is considered to be warm, around 80F/27C°. Summer waters are slightly cooler. In either season, you should not expect to wear anything more than 3mm but even this is too much for some divers. The are plenty of divers who wear just a 3mm shorty, accepting a few scrapes. Some divers choose protection based only on UV or the need for other protective layers.
If you tend to dive for longer periods, you’ll need to bear in mind that exposure protection just defers a gradual chilling, usually long enough for most people to get out and warm up.
You should not expect to require more than this unless you typically tend to be one of those divers get who gets chilly ‘everywhere’. Anyone who tells you that more than 3mm is the norm is likely just that kind of diver themselves.
There is of course nothing wrong with wearing more but for the consideration that Bonaire is generally ‘hot’ weather. Increased thermal exposure protection will increase the risks of overheating prior to getting into the water.