The only problem with relying on a rating system is that they tend to get biased to the ones best marketed, or simply most popular even though something else is better.
Its a difficult thing to create a good marketplace IMO. But maybe the best option is a curated collection by MOD (perhaps these would be all free, basically the current collection), and then an open marketplace where anybody can upload anything.
One complication I realized with purchased plugins is: what about pedalboard sharing? Would you still be able to try a pedalboard with purchased plugins? Would you need to buy all the plugins first? I suppose this could be worked around if MOD has internally its own mechanism for DEMO plugins (cut sound after 5 minutes or something), rather than each dev implementing their own methods. This way any pedalboard could be shared and any "for sale only" plugins would automatically convert to demo mode.