Experimental Villager changes

I don't really see the need for Villager Rebalancing. Minecraft is a sandbox game. If you don't want to use a feature then you don't have to - Villager discounts apply only to the player that earned them - if you want to pay 44 emeralds for a Unbreaking III book then you are free to not to heal villagers and pay that amount. I suppose there are more problems on SMP servers that allow PVP because some players will be able to get OP armor and tools faster than others,but thats always been true as players choose their own priorities when building farms and villager trading facilities. 
If Mojang is concerned about how cheap trades can get using the healing mechanic then they really only need to limit the number of times it works or by how much it works which as far as I can see. I have mixed feelings about the biome specific changes that they are proposing - in one sense having just spent nearly an hour rolling the trades to get an Unbreaking II or III book it would be nice to have a smaller number of possibilities thus reducing the time it takes to get the trade you want  I have never considered the villager trading as OP because to do it properly is actually a lot of work.