If anything a downloaded song from Match will take up more room than is you synced it directly from iTunes. This is because you have the option of downgrading to 128kbps when syncing directly, whereas a match download will be 256kbps (if matched) or the original bitrate if uploaded.
As for deleting the files from your phone, it looks like the problem you have is deleting it through a playlist.
You can delete all the music off of your phone through settings/ general/ useage and then select Music from the storage section at the top of the screen. If you then swipe across All music you can delete all the music downloaded to your phone.
Otherwise, you can delete songs individually, by album or by artist. I don't use playlists on my match library, so can't really report on your problem, but I imagine that is due to you deleting through the playlist.
Hope that helps.
Edit: I just setup a test playlist and added a couple of albums which I downloaded to my phone. I was unable to delete them from the playlist view, but when I deleted them from the artist view it didn't effect them in the playlist. Perhaps there is a specific issue I'm missing which is causing them to be deleted from your playlists.
Thank you for the answer. I actually meant to say "correct answer" instead of just "helpful answer."
After I posted this, I finally came across another post you were involved in (elinimnate songs from device after enabling iTunes Match, https://discussions.apple.com/thread/3593632). Your answers there were helpful in addition to the additional replies. Good to know that I'm really not alone on this issue. Hopefully, like others replied, an update will fix this to be more useful.
The Pages and iCloud need to be fixed as well. I think iDisk is more useful and don't understand why they went away from that with respect to documents and files. If Pages were to be the "new" iCloud file storage, at least it could have the ability to create folders for documents so you don't get overwhelmed by your separate documents. It also needs to work better with Pages on your computer, especially when creating or editing a document on your computer.
Again, hopefully this will get better with future updates.