If you just want to see the fish and your jig then you might as well pick up a zercom or green box off craigslist for $25.
Just like your open water fishing rods. They will all do the job, but doesnt a good quality one help you catch more fish? The rod doesn’t catch fish for you, so why not just use $10 walmart rods? Why? because you can feel more fish with a good quality rod and thus catch more, well with a good quality sonar you can see more fish and see what your lure is doing. Ice fishing is a visual game, you need to be able to see your jig, see the individual fish, and see how they react until that tip moves. With a unit that just shows fish, your jig, and the bottom, all you see is your jig dropping into a mass of red or gray. If you go for the better units on the market you can see your jig between the individual fish (perch, crappie, bluegill, walleye etc) and see how each individual fish reacts to your lure. No more fishing above the school and getting the aggressive little ones, now you can fish IN the school and work those big slow fish.
They all do the job, but some do it BETTER. That is hard for most to understand.