WAD. DESKTOP doesn't start Explorer, it starts userinit.exe (which runs logon scripts, establishes network connections, and then starts Explorer.exe.)
The purpose of DESKTOP isn't to emulate 100% SysInternal's version, and it's certainly not to create something too encumbered with options to easily use. If you prefer the SysInternal version, use it.
Userinit is too heavy-handed to be the default. I'll bet it leads to problems.
I had to alter my logon script so it wouldn't do nearly all the things it does at logon and anyone who uses a logon script and TCC's DESKTOP is likely to need to do the same.
Network connections span desktops; SUBSTs span desktops; SHRALIAS spans desktops. As for other apps (email clients, et c.) it's questionable whether users will want second instances, whether second instances will even start, and whether a second instances, if started, will interfere with the first (as happens with PowerPro). The only thing in my logon script I want done on a second desktop is to inject a middle_button_double_click mouse hook dll into explorer (and that I can do with a "DESKTOP ... START /DESKTOP ..." alias/script).
Please give us options. ... don't auto-switch, start userinit (/I), start just explorer (/E), start something else (/P ...). I'll configure new desktops as I see fit, with aliases or scripts that use START /DESKTOP