These are all valid points, but there should also be a discussion of the infrastructure. For journals published by a publisher (such as Sage), the whole publishing process is taken care of. Marketing, as well as revenue are covered. Given that academics take the task of being editors and grad students usually act as managing editors, the material circumstances and time commitments are also important aspects.
The Canadian Journal of Communication - open access- has managed to do very well and even bring in some profit.