What needs improvement in Appium is its documentation. It needs to give more context on the libraries that Appium is using under the hood. For example, my team is using Appium for Android automation, and a lot of times, I feel that there's functionality that's available through the Appium interface, that exists within the UIAutomator, but there aren't a lot of useful or helpful resources on the internet to find that information, so it would be good to have some linkage with the underlying platform itself.
Another room for improvement in Appium is that it's buggy sometimes. For example, at times, there's a bug in the inspector application that doesn't allow me to save my desired capability set, so it would be nice to get that bug fixed, but overall, Appium is a good tool.
The Touch Actions functionality in Appium also needs improvement. For example, if I want to initiate a scroll on the device that I'm running Appium on, sometimes Swipe works, but in other situations, I have to explicitly use action chains, so I'm not too sure what's the better approach.
What I'd like to see in the next version of Appium is a more intelligent and more intuitive AppiumLibrary, in terms of identifying menus and scroll bars, etc., because right now, I'm unsure if I have to do a lot of export reversals to get to the elements I'm looking for. It would be nice to have some functionality built in, which would allow me to easily get those exports.