>> doesn't this indicate quite a poor architecture In my opinion (I've used Mathematica heavily), no. My best guess, they are able to develop the modules and

>> doesn't this indicate quite a poor architecture In my opinion (I've used Mathematica heavily), no. My best guess, they are able to develop the modules and capabilities separately, i.e., divided cleanly into multiple teams. Their choice of keeping it closed source is orthogonal and does not indicate a poor architecture.