Why is it branded as savings? If they're 30% faster, that's 30% more profit, no?

30% more revenue. And this is in a marginal industry. Bitmain can keep adding miners until the difficulty pushes all non-ASICBOOST miners out of business as their power costs exceed revenue, but Bitmain (who pays the same for power) would remain in business. This has already happened: see KNC miner.