Recording a piano is always somewhat of a compromise. The different permutations of mic choice, relative positioning and overall mic'ing schemes each have certain advantages and certain unavoidable side-effects. It's therefore a trade-off between the desired qualities and undesirable side-effects, which is a subjective decision made by the engineer/s, producer and musician, largely based on how noticeable those undesirable side-effects are likely to be. The obvious difficulty is that this can only be judged for a majority/percentage of listeners because different playback equipment, playback environments, freq response and playback volume can all affect the notice-ability of those side-effects. In other words, the "huge mistake" could, in effect, be yours! Some unintended consequence of your particular playback circumstances, for example; something as simple as a higher playback level than the expected playback volume range. This isn't definitely the case of course, mistakes (and/or misjudgements) can certainly be made but the two recordings you listed were made by Decca and EMI, two of the most knowledgeable, experienced and influential labels in the history of music recording, so the chances of them both making the same mistake are rather unlikely (though not impossible).
That would be a good idea. A couple of 10 secs or so snippets of the bits which exhibit the phenomena you are talking about. There are numerous different potential causes of what you've described and identifying what's on the original recordings themselves will help narrow it down.
G
