I would agree with you that there is the need for more ramps faster. For the past several years, there has been an accumulation of ramps, with usually a half dozen to a dozen of new ramps/year (which sometimes multiple ramps/game).
Ramps are not 'simple' - as there are often additional parts flaps, hardware, as well as decals, so all of this needs to be created and run. Not to mention the costs and complexity of the ramp molds, which sometimes original molds exist and sometimes they do not.
Also, to make ramps, you really need to make say 100-250 of them, and then for the hardware 100-250 of anything gets expensive, etc. So, it's a tricky proposition to make a ramp and price it so you can stay in business - which is why primarily you see the major game ramps being redone, but anything like a B or C game it's difficult to find the customers or support a price to get your cash back out of the project quickly - not for the faint of heart ...
rick