Most want to leave the recordings unadulterated in order to give the best representation of the gear possible to other tapers. Many times, someone will say "I'm trying to decide between X and Y - which should I get?" and people will tell them to check out sources of each - if they are mastered sources, it piles on more factors in the decision making process, and determining the true capabilities of the gear. This is also why people are totally neurotic about sourcing... I personally buy into this.
There are also people that argue that post-processing is messing with an otherwise accurate historical representation of the event as it actually happened. I agree with this less, as many things that the taper does will have an effect on the recording and its accuracy to the recording in a historical sense: mics, caps, mic placement, mic config, mic cables, pre, recorder, A/D, sample rate, mistakes, and bit rate all are variables.
Of course, there are a vast number of people who really don't know how to master recordings, and I'll count myself in that category. But, I don't think that encouraging people to do more mastering is going to result in more good recordings, as most people will make them sound good on the system on their computer, and when played on many other playback systems, it'll sound like crap. That doesn't mean that people couldn't learn to master recordings effectively, just in my experience, mastering is the most difficult part of recording...
I know a lot of people here, especially shun compression...
Definately interested to hear your opinion.