You make it sound like MMA is better than Matlab for even numerical work. Is this true? For example, would machine learning algorithms be better code in MMA than Matlab? Matlab right now dominates engineering and in particular machine learning.
Matlab is all over finance as well. I haven't used it personally so I can't comment. A lot of quant finance is matrix driven, something which Matlab was made for. Mathematica is perhaps a bit more algebraic and general purpose, but again I don't know much about Matlab's capabilities.