Actually, I do not think shore diving is dominant in Curacao, although I think it's increased quite a bit over the years as word has gotten out. To someone focused on shore diving it may be seen as dominant. To someone who prefers mostly boat diving, it is not. I don't have statistics, and I don't even know if statistics exist, but I would say there has been more of a balance between the 2 on Curacao than Bonaire.
The diver that is attracted to Bonaire for shore diving may also be attracted to Curacao. But the reverse is not necessarily true.
Divers do more than dive - they still need to get there, stay someplace, eat, and probably get around. Sometimes they would like to do something else for a bit. For better or worse there's a ton more stuff on Curacao. Some people care about these things more than others, but they're certainly relevant to divers.
Access to shore diving is different. There's fewer places on Curacao with a good and easy access house reef. For diving around the island, people have long complained that you could just drive along the shore in Bonaire and hit multiple sites, but on Curacao you had to drive along inland then head out on spur roads to the coast. Used to be most folks saw this as a big negative because of the time it took to travel between sites. Eventually, people also figured out that on Curacao those spur roads ended at pretty little beaches, with easy entries instead of ironshore, and often facilities, where any non-divers could come along and enjoy the day too. And that often they should stay put for a half day or day and do a few dives, instead of traveling site to site with a truck full of tanks. It's a different model.
The underwater topography, whether boat or shore diving, is pretty different. If you only care about the critters and being wet, you may not care. But there is a lot more similarity among the sites in Bonaire. If you are into topography at all, there is more variety in Curacao. Bonaire is off the continental shelf, and Curacao is on the edge. Since the islands are relatively close one could easily assume they're the same underwater, but they're not. (Aruba looks like it ought to be the same too, but it's completely on the shelf, and we all know it ain't the same.)
Curacao tourism is not nearly as much about diving as Bonaire is. Bonaire does a lot better with real, convenient dive resorts and tank pickup options. Being smaller helps. Curacao has always struggled with this - good places have come and gone, and the compromise between distance to resorts and better dive sites and anything else is real.
oops, turned it into another comparison thread...