My current stand is made of 2x4's also... and it is good enough. Personally not a fan of curved angles for the exposed parts, and when I tried to square off 2x4's the bowed a lot. Still learning here... new to woodwork and thought the idea is pretty cool, although it's more work.
If you're new to wood then stick with tried and true methods. Better to over build. I am into woodworking and I don't think I'd ever use 2 x in a fish stand cabinet. All 3/4" plywood and 1 x material. And almost no screws. Use them more to clamp than structural. I use to be old school on the screws too. regular wood screws with a pilot, shank and countersink. Been using these new (to me) spax screws and liking them. Not brittle like DW screws and without the work of a conventional wood screw.