It's because Wayland is a set of protocols, rather than a single dominant implementation.
In order to do it right, cross-compositor and flexible, you have to get different actors with different interests and bandwidth agree on a standard. This takes time.
In order to get it working fast, developers need to make a compositor-specific implementation first and then put in the extra work of getting it through the standards discussion as well as switching their compositor ecosystem to the new standard.
Until this happens with all parts that you care about, you're going to be annoyed either about interoperability or functionality. Pick your poison, and cue Moxie's "The Ecosystem is Moving" blog post. Also, keep using X11 until Wayland has the features you want. Most DEs/WMs haven't ripped out X11 support yet, and hopefully won't until their support of Wayland protocols is solid enough.