Hawkevil
Toast Wiper
You seem to be missing how IRs are made. Essentially a cab is miced up and the preamp out is also recorded, then the preamp signal is "subtracted" from the mic signal. All IRs have some sort of power amp in them and you would be hard-pressed to find one not using a tube power amp. What is it that you want to do, take the signal from the power amp output? Then what? You're still missing the speaker's coloration. What a cab sim does is impose an EQ curve on the output signal that mimics the EQ curve of a specific speaker. So in this amp you have the ability to record silently either with the preamp and an IR or the full amp and a cab sim. If you want a better option, put a damn mic on the cab.
Most commercial impulses like Redwire or Recabinet uses a flat power amp meaning it essentially takes it out of the equation. A lot of impulses keep the power amp engraved in the fliter yes, but definitely not all.
Add the fact that the 6505's tone relies quite heavily on the power amp section gives plenty of reason to want to record pre and power amp.
Okay, admittedly I had always assumed a line out was pre and power amp. I've never needed to use one before. The point still stands though, why give these options without the ability to have a pre and power amp output with no annoying EQ filter disguised as a mic sim?