I wouldn't say it's completely irrelevant -- MMSes are heavily compressed by every phone OS I've ever used. Wikipedia lists a "recommended limit" of 300 kB[1], and Verizon's developer site lists a hard limit of 1.2 MB[2].

[1]: http://en.wikipedia.org/wiki/Multimedia_Messaging_Service

[2]: http://developer.verizon.com/content/vdc/en/verizon-tools-ap...