I expect the WP app, be it the desktop or the metro version will see a big update when we're ready for WP 8.1. As far as the metro version of the app lacking things, I chalk that up to the WinRT framework being new and a v1.0 product. In Windows 8.1 though they've added over 4000 new APIs to WinRT which expands the functionality a good deal more. So with Windows 8.1 and the updates to WinRT then we should expect to see the app itself updated and able to do a lot more. They know people want it, it's something asked for for so long, just like with the default Mail app in Windows 8. Now the new one coming with 8.1 is a huge improvement and I bet it's due to the new APIs added.
That said, the desktop app should see a good update as well to match and bring back lots of the things Zune did well that are missing.
One thing to remember though, and why these apps aren't as feature rich from the start. The goal with WP8, more so than WP7, is to be as device independent as possible. What I mean by that is to not require you to connect it to a PC/Mac unless you want to or really have to for something specific. The phone/OS will work just fine without ever being connected to a computer via USB actually. Heck, the fact you can do a big OS update without connecting to the PC at all now just shows how much they want to untie it from the need to have a PC which limits who can buy it. The Lumia 520 would never have had as much success as it has in low income markets if the OS needed you to connect to a PC to do lots of things which you had to do with WP7.x.
Anyways, long story short, expect updates to the apps after Windows 8.1 is out and Windows Phone 8.1 is near.