Even if we assumed your assumption was correct:

Let's assume an average $12 fee now (probably will drop back to lower levels)

$200 - $12 = $188

If we assume your thesis that fees will increase at the same pace as the savings:

$20,000 - $1200 = $18,800

Yeah, I'd rather have $18,800 stored safely on the base layer, vs storing that amount on L2.