Wandering Trader trades depend on your progress.

A lot of people get upset by seeing the Wandering Trader, as it just gets in the way, and doesn't sell anything they need. This isn't a perfect fix, but it a should help. What if the Wandering Trader determined trades based on your achievements/advancements for that world. This could include which biomes have and haven't been visited based on the "adventuring time" and "hot tourist destinations" achievements. Obviously, it shouldn't be something that let's you get more stuff without trading. The Trader wants you to be a returning customer, so probably wouldn't trade something like a map to somewhere. Cheap stuff like saplings or moss would still work, since it's cheap enough. Imagine you haven't found a mountain biome yet. Then the Wandering Trader comes and trades buckets of powder snow. I think it could be useful. That's just based on those 2 biome dependant achievements. It could also unlock and/or lock if you have or don't have a certain achievement. For example, if you don't have the "what a deal" advancement, they could give a way to get some emeralds, I'm thinking it could have something to do with ingredients for invisibility potions. Another one could be if you've gotten "aquire hardware", but have yet to get "ol' Betsy", the Trader could trade crossbows (for a higher price than fletchers, maybe). I think this could give some use to Wandering Traders, and has so much potential that I'd like to see used.