A pre-mastered tone is bad because it's limiting, it becomes a one trick pony.  You wont necesarily agree with the decisions made in making that sound, the mic's used, placement, mixing desk, onboard compressiona nd eq and so on, and there is no way of getting back what's been cut out of the sound should you want it.  You don't need a sound that's already been mixed into the background.

If you ever go through another amp treating the unit as an fx unit/pre then you also just want the resulting sound to sound like having that amp, not that amp recorded by such and such, but literally like you have plugged into that amp and you have it there (as much as possible within the confines of your own cab and the power section of your amp).

There are many reasons for not wanting a pre-mastered sound.  Sure I like having the option of some preset "mastering" effects that I can add at the end of the chain if I want to, but as they're always destructive, i.e. taking away part of the sound that you can't bring back, then I want a neutral sound, and to sculpt that sound from there.  This is a particular problem as with the PodHD I feel the sound is lacking in the lower mids in definition and punch, it sounds thin, and sits in the background in a mix, it's hard to push through a mix with it, if you raise that with an EQ you get a very undefinied boxy and "flubby" sound.  It's an area where most of what people think of as the warmth comes from and also one you really need if you want to stand out in the mix.  It's mixed and mastered to the background not the foreground.  Ideally it shouldn't be mixed to either as that choice should be up to you.

That's why a pre-mastered tone is undesirable and why you want as neutral as possible (with the optional convenience of preset "master" effects).

Hi, thanks for the feedback, yes I've used that link and sent in some requests.  We'll see how that goes.