Dear TickleMyPickle,
I would argue with you on those lines: "I feel as if it would take too much work to accomplish what you suggested, yet it would yield petty results" and "nobody prevents you from messaging a player via /msg".
For "I feel as if it would take too much work to accomplish what you suggested" line, I will say it's easy to deal with the main parts of this, using the same codes we already have with selling
-You can put a table nearly the same as the table we have with /listed, which we can use 2 seperate ways of dealing with the problem when u want to put an item that u need to buy
+ An annoying but universal way that most people know: The selling table can open another table to choose the item u need to buy, writing the amount u need and the price u offer. (This encounter tons of problems, such as enchanted items, etc)
+ My proposing way: You need to have the item u desired (ranging from 1 to 64) in hand and writing a command for like /buy [Amount of stacks] [Price], so if u want to buy let's say, 100 stacks of 64 sands for 200$ each, u would need to hold 64 sands in your hand and write /buy 100 200. And the items that people sold u in from using this will store in another table like /listed so u can collect later. This actually help people to buy a big amount of items for a shorter amount of time, and prevent new players from flooding the shop and buy such famous items as enchanted item/armors or elytra, beacon, etc...
For "yet it would yield petty results" line, I would say, yes, to the people who already diving into the economy, but i would say no if u considering the player base. Implement a way to passively buying stuffs from people will help the buyer and seller to use their time more effectively into the interesting parts of the game (building, pvp, etc), and it would respect the player's time, which would increase people satisfaction on the server -> better the server's image.
+This also would reduce the need for building up self-image, which is a hard thing considering our playerbase's average age
+This wouldn't meant it would delete the ways people are selling and buying rn, owner can just limit the amount of stuffs u can ask for buying to make it not being "infinity buying". Thus preventing the deletion of current ways of trading
For "nobody prevents you from messaging a player via /msg", Yes, and also nope, most people refrain themselves from asking people directly, considering our regular education on the average age of people who play this server. And to change this, we need to better our whole regular education, which doesn't contained in just a community.
Regard,
-DezS