This greatly depends on the hero and the course of the game. I admit that this meta isn't terribly favourable for that sort of greedy midas, but you're acting like it's universally bad and that's just not the case. I don't understand where the 30 minutes number comes from, either, given that it takes about 18-19 minutes of efficient midas usage for it to pay for itself. Unless you get it really late I just don't see how 30 minutes makes sense.
All this not even taking in to consideration the fact that you seem to be functioning under the premise that midas is useless for anything but the active, which isn't true. Many heroes benefit from attack speed in a big way such as slark, clinkz, or naix, which are the hard carries whom I like building midas on most. Slark benefits greatly from the higher xp/min but clinkz and naix don't really give a shit for xp past like level 9 or so.
preemptive... Yeah, clinkz can be played in a more semi carry role and go for early aggression, but that's not what I tend to play. Attack speed is strong because you get quite a bit more harass with your orb any time there's an enemy hero around.