I agree with your first sentence, but disagree with the second. That you can find an exact mapping does not prevent the underlying API from being more complex than what you need. That you had to realize "Oh, m=2" is more complexity.
I'm not arguing this is a terrible thing. In fact, I think this is an acceptable level of additional complexity for the power it buys you. But if we're going to make an honest evaluation of the trade-offs, I think we must mention this.
It may be relevant to the discussion to point out that I work on a tuple-based streaming system. Product: http://www-01.ibm.com/software/data/infosphere/streams/ Academic: http://dl.acm.org/citation.cfm?id=1890754.1890761, http://dl.acm.org/citation.cfm?id=1645953.1646061
