MathType has the nice feature that when you click to insert a matrix, one has the choice of immediately inserting a typical low-dimensional matrix (i.e. 2x2, 3x3, 3x1, etc), in addition to the option of setting the row and column numbers manually. As far as I can tell, in Lyx you must always specify the dimension explicitly. I find this a bit of a nuisance and thus make the feature request.
Thanks to the Lyx team for their great work and their consideration of user feature requests. Jim
