Those are some good sources (though I'd take a number of them with a fair amount of salt); at the very least, it does appear there is a scholarly consensus that the Roman Empire had plenty of other options for financially maintaining their empire (even if economic history scholars would disagree on the particulars, as they are want to do).
I'm not trying to be a dick here, although I suspect I'm coming off as one. But I think there's a lot of misconceptions about the Roman state, i.e., its hostility to trade.