To answer the initial question, no it isnt necessary.
It is preferable though, as wavemakers will provide a more natural like flow in the tank, which is good for detritus suspension as well as for coral growth.
However, I would make the point that slapping together some wave making using a number of powerheads on a timer is a bad idea. Not sure if you've seen the pictures of people who had fires from using the cheapo setups that are out there. Anything that is constantly clicking powerheads on and off is a bad idea from an electrical standpoint.
Much better would be to invest in the Tunze wavebox or a set of tunze streams on a controller. Even a sea squirt on the return is a better idea. These approaches are more expensive but are better in my opinion.