Where does one find these magical accounts? In many countries no bank pays interest on current accounts, or, where they do, currently interest rates generally are so low anyway that the amounts are negligible. I have much better ways of arranging my finances than faffing around with credit cards I don't need and moving money around short term money market accounts just to earn less than $20 extra a year.
As for your example of buying something online with a debit card, I don't do that. My bank lets me generate as many virtual cards as I like for online shopping, each with a different number. I set the maximum amount that can be charged to each one and I can then order anything I want online with it with none of the risks you mention.
Even if I couldn't do that, the situation you describe wouldn't arise, as
a) I have daily limits on various types of transfers and withdrawals (that I can adjust online if I need to spend more than that at any time, so I keep the defaults pretty low). So even if someone was being malicious they still couldn't take out more than that amount (and I've SMS notifications set up for all transfers over a fairly low limit too, so they couldn't just come back and take another payment every day until I was cleaned out). It would certainly inconvenience me, but that's just as true with a credit card (and that would probably take me longer to notice). And, as I said earlier, I've had experience of problems with both, and the credit card ones were much more hassle to resolve.
b) my current account is multi-currency, so even if someone managed to clean out all my euros, I'd still have cash in GBP, USD, etc.
c) most of my money isn't in my current account anyway, so even if that got completely cleaned out, in all currencies, I'd still have money in my various other accounts.