You are using it, if you either need a dynamic second dimension (unlike multi dim arrays which have fixed sizes for the second dimension) or if you need slicing support.
That's a recursion. In BlitzMax till now array slicing is only allowed with 1D-arrays. That's why we have to use them. So saying "use them, because you need to use them" isn't what I was asking for. In fact I'm currently using arrays of arrays, but this isn't the proper solution for a problem where a fixed second dimension is needed. Yes, sometimes a dynamic second dimension isn't an advantage, because in these cases (as posted above: pixels in screen, characters in command prompt...) you need to have a fixed second dimension.So in such situations a 2D array would be the best solution. And as I already said multi dimensional arrays are available in BlitzMax, so why not use them if you need them?
It's just that we would need some features for better handling them -> array slicing/concating.
Of course there's always a way to do something without this feature, but I didn't said "I'm having a ploblem/how to do this?" - of course there's a way to solve my problem till now, and I know this way, but I just think that the language gets more self contained with this feature.