I like it just on principle for being something the Canadian banks collaborate on
without involving Visa or Mastercard, unlike in the US where debit also goes through their networks.
From the consumer side, I don't use it all that often for purchases just because I'm aware of the interchange fee tax on cash purchases so I try to maximize the value of my credit cards: 3x Avion points for grocery spend on RBC ION+, 2 Aeroplan pts/$ for dining on Amex.
As far as a requirement to be online, given the nature of debit that doesn't surprise me; the whole point relative to credit is that no one has to trust you to pay a bill later. If offline transactions were possible then it would just be a credit card by another name.
The refund thing surprises me, but I expect that has to do with preventing some fraud scenario, maybe like an inside job where an employee issues remote refunds to a confederate? Overall it seems like the design of the system is fairly conservative and that's reflected in the much lower fees; the whole point is to not have to have whole armies of people answering the phones to help grandma get back $50.
