These are the reasons why they merchants might possibly want Bitcoin, in addition to the ones outlined in this thread.
(1) Simplicity and user-friendliness for the user. Granted, currently Bitcoin is overall a crappy system for the user to use. It's a pain to purchase or sell Bitcoins. AMC/KYC (compliance) requirements have ganged up on us, scammy exchanges took our money, and what not. However, if everything is set up well, in theory merchant can simplify the check out process greatly. Just provide bitcoin address, money sent, done. What happens with merchants usually? Credit card number is never enough. Expiration date, code on the back of the card, billing address, zip code, telephone number, address. Frequently this information has to match with the information that the bank has on file, or else checkout fails with no reason given. Now with 3d secure they also forward to bank page that asks additional questions. I have a hunch that by doing all that they might be losing sales. It's not just - "ah, let me just do this check out real quick", no, it's usually, let me provide all this information that merchant asks to satisfy their risk management strategy and hope it that it will work right away. In addition to that, fraud prevention filters are stupid as fuck. They are rejecting the transaction when the user is connecting from IP that is in different country than the bank account. Supposedly it is because that might indicate that the card was stolen from overseas. This is very crude and stupid system. First of all, there are false positives (I know from first-hand experience), secondarily I can't imagine that carders (credit card hackers) can't use proxies to bypass that.
(2) Business bank account fees. Visa/Mastercard funds have to go to a bank account. These bank accounts are directly or indirectly taking fees. It's not impossible to imagine that big retailers may be paying a lot of money for their bank accounts. I mean, I have seen consumer bank accounts that supposedly charge zero account maintenance fees when the balance is large enough. However, I have never seen a bank that for instance doesn't take international wire transfer fees. Big corporations may have a complicated tax structure so the funds might be going through several hops before reaching ultimate destination. Storing the funds in Bitcoins would simplify this process, because it would allow the merchant to withdraw the money directly to the ultimate bank account. Especially if other business stakeholders (employees, suppliers) would accept Bitcoin that would greatly simplify this process and reduce fees and costs all around.