This suggestion seems ridiculous at first, but the mechanic itself could serve to benefit the game.
Let me explain:
Encouraging catching Pokémon is beneficial to the market, and inherently the players. For example, should the shiny rate be universally increased to 1/35k, you could then earn a buff returning the normal 1/30k for that species.
The shiny buff could be earned through catching 10 of the species and this could happen every 4 hours(?). This would encourage something shunters passively avoid.. contributing to the market & catching Pokémon.
The buffs for the species could also vary in amount based on the number of GTL listings that species has.
Anyways, thanks for bringing this up!