sFTP requires the SSH protocol to encrypt all information transfered and as such any account that you wish to access via sFTP will require SSH access. Accounts are not generated by default with SSH access however can be enabled on a per-request basis.
An alternative is FTPES (FTP Explicit over SSL), this protects your FTP connection using the same SSL technology that protects online orders and transactions. This can be used without SSH access on the standard FTP Port 21.
As part of our security plan, our SSH port is on 2233 as apposed to 22 to help prevent brute-force attacks targetting the default SSH port.