Am I misunderstanding things? http://communities.vmware.com/docs/DOC-2527 suggests I'm not, and switching back and forth between bridged and NAT mode just to get disk sharing working seems like too much of hassle.
Usual caveats apply... e.g. Correct settings in Host and Guest OSes to enable File Sharing and Firewall Settings correctly set, etc...
You can access a Virtual Machine's Shared Resources from the Host whether the VM's Network is set to the default NAT or changing to Bridged much less Host-Only!
You can access the Guest's Shared Drive(s) or Folder(s) from Finder (menu bar) > Go > Connect to Server
e.g. smb://IP_Address/Share_Name or smb://Computer_Name/Share_Name
Obviously accessing the Guest VM from a computer other than the Host would not be accessable using Host-Only and or NAT without modifying the default Host network settings however when it comes to Host to Guest or Guest to Host all three will enable access to the other with the correct settings made.
No switching back and forth is absolutely necessary.
As far as the Cross-Platform Contamination that Parallels inflicts on OS X thankfully Fusion does not cripple the Host in such a manner and if VMware ever goes that route and enables it by default I will not be using Fusion any more and will just go back to a Windows PC and use Workstation. If VMware does go that route I'd hope it is a secondary install and modification of the Host as I do not even want it installed and disabled by default and I think there are plenty of other professional users that feel the same.