Hi Helaine, In my opinion, opening a bank account is not enough reason to go to the trouble of getting temporary residency in Argentina, especially if you are in the country just under six months each year.
You should be able to open a bank account with CDI which you can get from AFIP and even if you have a problem with that, you should be able to send yourself money by XOOM and pick up the funds in cash in BA using your passport as your ID.
A Charles Schwab debit card will enable you to make ATM withdrawals when you want and they will refund the transaction fees. It is necessary to open a brokerage account with an initial deposit of $1000 USD to get the checking account and the debit card, but those funds can be moved into the checking account and no minimum balance is required to maintain either account.
PS: I'm not sure which category of temporary residency you would actually apply for. In fact, it would take a great deal of effort to get temporary residency. You would have to deal with migraciones on an annual basis, pay their fees, get the FBI report, prove your source of stable foreign income, and/or...