Would a wave maker be beneficial in a Tropical Fresh Water set up?

A wave maker can vary the current and help prevent "dead spots" or areas where detritus will build up. A wave maker is a device that alters current; there are many forms, and they do not necessarily mean higher current or actual waves. I use alternating current devices in all my tanks, even if it is just a powersweep powerhead or a rotating attachment for a powerhead/filter.

Alternating currents are pretty common in rivers, and creeks.....the water may flow in one direction but there are many eddies and other alternating current locations. And lakes and ponds tend to have some sort of current, just as the ocean has current on a larger scale.

That depends on the type of fish you have

Some fish, like betta's and gourami's, don't like a lot of flow in the water, but a lot of South-American fish which live in the amazon do like strong flow, so they might also like waves :)

That depends on what kind of animals you're keeping.

For most freshwater fish and other freshwater animals, no.

Waves are no an important feature of most rivers, lakes, creeks, or ponds.

sure as long as its proper size for the tank and the fish are good swimmers. i have a few for my africans but the rift lakes they are native to have very srong currents so they thrive in that ensironment and actually see them swim in is for fun.