I just used a physical Suica card, I'd link tickets to it at the time of purchase, and had no issue with using it. Osaka had a weird subway system, but there, I could just tap my credit card.

Rural Japan expects cash fares, yes, but rural Japan also expects cash for everything else, so if you're in rural Japan, you should have enough cash on you to cover all your expenses.

In four weeks of travel all over the country (from Tokyo down to towns of <700 people, and every step in between), I don't think I've seen a single machine/system/vendor there that demanded exact payments, without providing change.

I'm not sure why the OP wanted hotel staff to exchange money, when ATMs are plentiful, and will all provide JPY when you stick a debit or credit card in them. (If using a CC, make sure you have a positive balance to avoid incurring CC cash advance fees).