On the other hand...
...I get the arguments about pre-installed apps and bandwidth wastage. The appropriate implementation would have been a .pdf on the Desktop instructing users downloading an 'educational' image how to install Mathematica. Or, have an image for download optimized for secondary- and post-secondary education that has Mathematica installed. Problem solved.
We need to remember that a primary goal of the RPi Foundation is the creation of a computer that is cost effective enough for even extremely poor school districts throughout the world. I think the theory is that we will build global wealth and address income inequality by helping others get the tools they need to build up themselves and their societies. Will it work? Who knows ... but I sure think this is a more decent and ethical approach than hand-outs and whatnot that just build dependency and help the richer people maintain a degree of smug superiority. AND we get and outstanding piece of kit; what's not to like?
To that end Wolfram Research (Mathematica) contracted to provide free access to Mathematica. This tool is absolutely fantastic for the physical sciences, theoretical and applied mathematics, and electrical engineering. I've used it for all three and one of my organizations spends literally tens of thousands of $ annually on contracts with them and does so gladly. My first exposure was on a NeXT Workstation (remember those?) at university in 1992, at which time we were told it would revolutionize pure mathematics. It did. And now Wolfram (the man) wants to share his creation, I say let's raise a pint but also eliminate the download pain.
Sure, offering this free on educational kit is kind of like offering hits of an addictive substance ... the marketing hope is obviously that students will get hooked on Mathematica and when they are in a position to purchase software later in life will tilt the scales in Wolfram's favor. Worked for Apple back in the day. But I'm just happy if we get disadvantaged students to the point in life where they are making software decisions.
Disclaimer: Yes I'm a major fan. But I also use MathCAD, Matlab, GNU Octave, Maxima ... basically whatever tool will make a specific job easier. I am a software polygamist.