Sorry for your loss, but you may have came out cheap. I can just imagine the poor soul spending hundreds if not thousands on a expensive U/W strobe system only to find out that there are inexpensive units that do the same job if not better.
Zoom lenses have come a long way from the Vivitar zoom days but the will not replace the True Macro Prime lenses.
Primes can focus much closer (true macro), are much brighter for quicker focusing, the least amount of lens elements makes for better picture quality and the fact that you would need a special lens port for your U/W housing just to control the manual zoom RING on a DSLR camera (the point and shoots use an electric motor to adjust the zoom). This will add to the cost of the U/W housing.
Yes for TOPSIDE photography like for the amateur weekend wedding photographer, where you need a wide range of lens sizes real quick, the zoom lens is the way to go.
With U/W photography the waters visibility will determine the type of lens you would be using, at poor visibility you better have lens that can focus really close and have a real bright screen. U/W photography is a slow methodical process, knowledge of the subjects behavior; light balancing, strobe placement, camera angles etc come to play.
I usually start with a recon dive on an unknown reef with a close focus wide-angle lens and wide-angle strobes to get an overall feel of the environment. At the same time noting down any macro opportunities for the next dive when I switch lenses and smaller strobes to macro. Some divers just take several cameras with them.
I just hope that your experience with a lower cost housing manufacturer, does not discourage them from making their lower cost products if only to keep the competition honest.