This sounds good, but I see how players would start complaining if that happens. Think about this hypothetical situation:
-All the players are waiting excited for the week in which Farm Perk will be selected
-That week finally comes
-All the players start getting their gears to Uber because they want it.
-Only 20%-30% of players are lucky enough to get it
-Those who didn’t get it spend gems to remove the other perk and try again
-The failure and spending of gems can repeat many times…
-Players complain a lot because they think it’s just another strategy from Flares to make them spend gems
See? Some players might get confused and think that 20% or 30% would mean a 100% possibility of getting the perk they want, they believe in a relatively high percentage and really hope to get that perk, so they get disappointed if they don’t get it.
Others would just ignore the weekly stuff as they don’t like Blacksmith anyway, or they might stop using the feature for a week if a terrible perk is selected (I don’t imagine having a 20%-30% probability of getting something shitty like Toxic Cloud).