The simple query widget only allows to set the join type when the condition just have 2 attributes.
The simple query should have the same options if the condition has more than 2 attributes or variables.
LEFT OUTER JOIN TABLE2 ON (TABLE2.ReferenceId = TABLE1.Id AND TABLE2.Something = @SomeVariable)
This is not the same as:
LEFT OUTER JOIN TABLE2 ON (TABLE2.ReferenceId = TABLE1.Id)
WHERE TABLE2.Something = @SomeVariable
I can't do this with the simple query, and I'm forced to use the Advanced Query just to say that the condition is a Left Join and not a normal Join.