This app was mentioned in 7 comments, with an average of 2.14 upvotes
Some of those problems can be fixed with apps and/or Tasker/WearTasker.
While Google doesn't always get it right one thing I love about Android is that with it's flexibility you can usually find and or make a fix to something you don't like.
This is what will always bring me to Android over Apple.
Edit: some examples I know of are start a non-Google music player and start a Hangouts conversation.
I'll just add a link to the actual app since OP omitted it: https://play.google.com/store/apps/details?id=com.barkside.music&hl=en Looks interesting. I'm currently using "Music Boss", but will gladly try out another app to see if my music controlling needs will be met in a better or more consistent manner.
This app should let you start the music on most music apps - it works on my Sony phone with the Sony music app. Selecting playlists dosn't work, however.
https://play.google.com/store/apps/details?id=com.barkside.music
Wear Music Controller lets you start music from your watch - works for me with the Sony music app. I don't use Google Play Music, but it says it works with GPM and says its experimental play feature lets you select playlists. Here's the play store link: https://play.google.com/store/apps/details?id=com.barkside.music
OK that makes sense, I just wanted to make sure you knew about those touch controls in case you never swiped the card.
For extended voice controls for music, you might check out this app:
https://play.google.com/store/apps/details?id=com.barkside.music
I don't have it personally, but the description claims to support voice activated music controls.
Wear music controller is a must for me.
I don't use any of these two, although I'm familiar with both. Using the watch as a remote for music playback, play, pause, volume etc is definitely part of what I want, too. Top of the list of apps I'd like to see.
Related to music remote control over AW in general, I've seen, but not used, part of that functionality which is available for Squeezboxes with one of the Squeezebox control apps, although can't remember which.
Likewise for Kodi with the Yatse remote. Since it's very poorly shown in one video from 2015, it's hard to judge what the actual functionality in AW is. I guess you could use F2000 through Kodi, and hence get the remote that way.
There's also a remote called wear music controller which may provide what you are looking for for the Neutron player. There's the Unified Remote for Android Wear, to control your PC, and although it's advertised there are functions for Android Wear called quick actions, it's not transparent what's possible to accomplish.
Finally, there's the combination of Tasker!, AutoWear! with some effort may make it possible to do what you want.
Google allows playback control of their Chromecasts through the watch. Functionality varies depending what the playback medium is.
The reason I cannot be more specific about remote usage is I use my phone as my hotspot at home. Because of this functionality of a lot of apps on Android Wear will not work. No information on this from Google of course. Not even for their own apps.
Furthermore, Google Play store is poorly structured, and Google seems to push certain apps over others, searchability, which they pride themselves in, is very poor for AW apps, and all of the above varies depending on which version of Android you have on your phone. It's quite laughable now that Google postponed the update to AW 2.0. A lot of potential currently residing in Android Wear sells nothing. Google's AW strategy looks almost like Microsoft's failed phone endeavour. Opaque strategy and bleak future. Trust Google to be opportunistic.