I don't know how many matte-only inks are left on the market, but with respect to the matte v. glossy black and white inks I use, there are several reasons one might stay with matte only.
First, if one mixes their own B&W inks from stock MK, the cost can be close to two orders of magnitude less than the desktop, small cart cost of OEM inks. The current version of the matte only B&W inks I'm referring to are discussed in this PDF:
http://www.paulroark.com/BW-Info/3880-Eboni-Variable-Tone.pdf . They can be installed in any Epson printer that has third party, empty, refillable cartridges available.
Second, matte inks don't need the binder (read "glue") required to stick pigments onto glossy paper. Because of this they don't clog nearly as much as glossy inks.
Third, if you're doing "fine art" where you'll probably want to display the image under acrylic (or museum glass), you can tape hang the artwork as opposed to adhering it to a backing. I think this is both easier and better.
Fourth, on my wall, in actual display settings, the matte under glass often has a better dmax than the glossy inks/papers. It's all about reflections. Our spectros are measuring the dmax under ideal conditions. Normal room lighting is not ideal. Avoiding reflections off the surface of the paper can be important.
For me, the main reason to bother with glossy is for prints that are going to be displayed without glazing (including my gallery brochures). I'll be running my 9800 with the glossy B&W "variable tone" inkset in it today just to keep it from clogging, and once my large canvas show is over at the end of September that inkset is probably going to be pulled and the matte version installed. Keeping big printers running when one does only intermittent printing is a problem.
Paul
www.PaulRoark.com