Using the chain as data storage, rather than currency, costs everybody, because it increases the rate at which people are discouraged from running full nodes. It increases the costs of that dataset that cannot be pruned, and must be carried for eternity: the unspent transaction output set (UTXO), the list of coins available for spending.
I guess moore laws don't exist anymore in bitcoin land. When bitcoin has no laws, it doesn't mean moores law doesn't apply either.
Moore's Law isn't magic. It reflects that people push back against wastes of CPU time, disk storage, and other limitations to push technology to its physical limits. Processor speeds don't just magically increase. Disk storage doesn't just magically increase. The assumptions underlying Moore's Law (which isn't a real law) involve bean-counters identifying and eliminating wastes of resources that slow down systems and break them, just as much as they involve people inventing new technologies.
The threat from dust transactions may be on the un-glamorous, bean-counting side of technological improvement, but that doesn't mean it doesn't exist.