1) Usability Timers
Upon interfacing with a Banker or Merchant I have EXACTLY 2 minutes to do whatever I have to do before the game automatically shuts down the window and the banker or merchant randomly walks away. Yes, I've timed it. Exactly 2 minutes. I assume this is part of an idle animation system for them. Most of the time, 2 minutes is more than fine for a quick sale or to withdraw/deposit items from the bank, but isn't enough time if you're sorting through your list and trying to make decisions on what to keep/sell/equip.

Why shut down the window automatically when players are actively using it?

2) Bankers/Merchants Teleport at Random
Bankers and Merchants randomly teleports away at complete random. Example: I'll summon a banker, immediately go talk to him... and Titus Andromedon Tythis Andromo teleports behind me. In rare instances, I'll turn around, try to talk to him again, he teleports away once more. Why does this man not want to do business with me? I pay him good money, and I promise, I use deodorant.

While these are by no definitions game breaking they are incredibly annoying, especially given how much the merchants cost.