[toufka]

BUT, if you look at the codon table, precisely because it's base-4 and not base-3, many base flips are silent when coded.

By using base-4, there's enough space to permit lossiness of the coding itself - given the number of amino acids and the 3-NT encoding.

So you really aren't optimizing JUST for nucleotide encoding, but you're also optimizing in concert with 3-nt/AA, and 20AA codes.

So if you have to optimize for information density and fidelity, given X-nucleotides, Y nucleotides/AA, and Z AAs, and sample as much chemical and physical diversity in those AAs life has settled upon: X=4, Y=3, Z=20.

If we went with X=3, you might need Y=4 to get the same kind of fidelity, but that cranks up your energy costs by 30% (from 3 to 4 NT per AA).