Hi Ed:
That necessity really has more to do with the P.I.T.A. (
notice how "I.T." is in the middle of that abbreviation ? 
) file / folder security hurdles imposed above and beyond the pervasive User Access Control (aka "UAC") we've had forced onto us since Windows Vista.
The
C:\Program Files (x86)\Lockheed Martin\Prepar3D v2 SDK 2.5.12945.0\Modeling SDK\3DSM7\Plugins\XtoMDL.exe path is likely to be regarded by any version of Windows since Vista as a "
system" folder subject to additional 'protection' (
IMHO, in the real world, more-so blocking access by the end user ...than by any minimally-sophisticated malware).
So, IIUC, because of the equally pervasive menace of malware (and inadequate functionality of "anti-malware" software), even if we 'login' to Windows each time we start it, we may
still have to jump through hoops to get at our own "authorized" program installations in the C:\Program Files (x86)\ and/or C:\Program Files\ folder chains.
And sometimes if we create a "shortcut" to any executable program file, and edit its [Security] or [Compatibility] tab under 'Properties' to "
run with administrative permission" for our logged-in account / profile user name, we may
still have to manually grant permission each time, for such a program to actually run ...at yet another pop-up prompt !
Perhaps another P3D user might tell us whether there is an option in the otherwise reportedly 'over-the-top' P3D installer
s from Lockheed-Martin, which may be
different for the P3Dv2.x SDK (as compared to the main P3D 'sim' package) ...by allowing one to choose a target folder path somewhere
other than the default 'system' folder chain at
ex:
C:\Program Files (x86)\Lockheed Martin\Prepar3D v2 SDK 2.5.12945.0\Modeling SDK\3DSM7\Plugins\XtoMDL.exe
And perhaps
Arno can tell us whether and/or how he implements security access to that folder chain ...when users follow the default LM P3D 2.x SDK installation protocol.
GaryGB