For what it's worth, this is very out of date, although I think the ban setting is probably still the best way to achieve the exact effect you're looking for. MusicBee has the check box column, you just have to do a little more configuration with it than in iTunes. I use tick/untick combined with filters and auto playlists to manage what plays and gets synced, etc.
I have no idea whether the ticked/unticked status is available in the iTunes library xml, but if it is I guess asking for it to be included makes sense. But it's still not going to work exactly like it does in iTunes. You'd have to do something like make a playlist of all the unticked files and then set them to banned.
<dict>
<key>Track ID</key><integer>1592</integer>
<key>Size</key><integer>439121</integer>
<key>Total Time</key><integer>61872</integer>
<key>Track Number</key><integer>23</integer>
<key>Year</key><integer>2010</integer>
<key>Date Modified</key><date>2011-10-31T21:59:15Z</date>
<key>Date Added</key><date>2012-10-16T02:06:25Z</date>
<key>Bit Rate</key><integer>48</integer>
<key>Sample Rate</key><integer>24000</integer>
<key>Play Count</key><integer>2</integer>
<key>Play Date</key><integer>3455432967</integer>
<key>Play Date UTC</key><date>2013-06-30T14:29:27Z</date>
<key>Artwork Count</key><integer>1</integer>
<key>Persistent ID</key><string>DF256A474B841359</string>
<key>Disabled</key><true/> <key>Track Type</key><string>File</string>
<key>File Folder Count</key><integer>-1</integer>
<key>Library Folder Count</key><integer>-1</integer>
...
This is a piece of the itunes... xml... The 'disabled' means 'unchecked' it would be rather simple to assign as 'banned'.
As I said, I have no problem with the idea, of using the 'Ban' concept. The problem I'm referring to is the original 'Importing' music from Itunes. And that is exactly the 'Wishlist' question from the original person here from long-ago.
What musicbee did do: Was bring over Itunes Ratings:
<key>Rating</key><integer>80</integer>
<key>Rating Computed</key><true/>
That is 4 stars. You make it sound difficult to find the 'disable' key and call it 'banned'.
So now I got years of music... and have to refigure out what's supposed to be 'unchecked'... oh wait 'banned'.
But it would be easier, to just reimport... with the software able to 'ban it for me'.