I really think mongoDB addition would be a great feature to have. A lot of BI tools can not connect natively to mongoDB. Apart from the edge that it will give the Power BI suite, a standard ODBC and JDBC based connector suite would be a great addition for connecting to No-SQL databases. Cheers!
Yes as Mongodb is very popular and award winning db of recent times there should be a connector to this .I therefore strongly agree this for Big data visualization