I just have a VERY strong dislike of bare bottom tanks. I don't even like them in fish stores.
All of my tanks are naturally setup. Sand/fine gravel, driftwood and rocks, and lots of live plants. But that's my personal preference.
Except maybe artificial plants would be easier to maintain without compromising too much on the "natural look"
OP's tank looks like a grow-out only. If that's the case, then bare-bottom should also be OK as it would be easier to maintain.
Also, search MFK (bichir forum) for "experiment" to find a couple of posts where the OP experimented with different colored substrates and showed "before" - "after" pics of his bichirs to illustrate the impact. (If I remember correctly, the bichir chosen was an Endli and he had the best color with red substrate. With white it was washed out and with black it was too dark.