Hi Hugh,
Say i have
VI slot 1 using kontakt for Spics
VI slot 2 using Kontakt for Stacs
VI slot 3 using Kontakt for Legs.
VI slot 4 using Kontakt for Sords
Imagine i carry on for hours building my template for another 20/30 VI slots or so. Then i stop and realise i forgot to assign the Pizzicatos a slot next to the Spics and Stacs (for a more coherent order) so they can sit after the stacs in the mixer window. Even if i can move the actual tracks in the project window they won’t follow inside the mixer.
I can’t simply create a new instance on (say VI slot 40) load up the Pitz patch and then have them sit after the Stacs in the mixer window. They will only appear after the Kontakt instances already created (hence me just loading an instance in every slot to begin with).
I could resort to replacing the Legs patch with the Pitz, but then i would have to replace every other Kontakt instance after that, but what if ive created 20/30 more such as in this example… A huuuuuge timewaster 
As jose7822 points out its “Because of Cubase’s inability to sort VST rack Instruments”
Unfortuntely I can’t work with just Instrument tracks because i rely on the multi outs which Instrument tracks don’t allow (AFAIK)