Adlib is popular now, because it was dominant then. You have to realize how much more common the OPL was. Roland MIDI modules can fetch high prices on online auctions today while the common old sound cards with an OPL chip are thrown away as garbage. The contrast in price grows higher, which means you can get OPL hardware for pennies/free. Also, the emulation is much further than with MT-32.
Also, MT-32 is more pro => musicians => MIDI
while OPL is more common => hobbyists => trackers