Definitely, if the system was automated and never left Steem we could handle smaller deposits. However we incur significant transaction fees converting SBD to Bitcoin -> Litecoin/Ripple/ETH -> USD and back again. Tx fees tend to be fixed, so have an exponentially greater effect on smaller deposits. Too much support load too.

Our product is aimed at savvy Steemians who can afford to make a modest term deposit and won't miss their money while it's locked up. 200 SBD is a relatively low barrier in that respect, intended as a way people can trial the service without too much risk. Once admin time is factored in, we'd be losing money on a 200 SBD deposit.