When people criticize the 901s for "no highs, no
lows," they are criticizing it for the wrong reason.

Whilst the "no highs, no lows, must be bose", is true, it's still a
joke, and not meant to convey the full extent of its limitations.

If it was only supposed to be a mid-range speaker I would agree.
However it is sold with an equaliser as a full range speaker, so
one should expect some highs and some lows.

I wonder what you think the right reason for criticizing it is then.
Poor efficiency, poor dynamics, high distortion, peaky response,
or something else?

1. Simply flattening the amplitude response of a mediocre driver will not enable
it to equal the sound quality of a well-engineered driver with similar response.

2. Bouncing the sound off the wall to produce a sense of spaciousness is
aesthetically invalid when the recording itself is supposed to contain the
original acoustics. This effect might be fine for mono recordings, but it is
antithetical to a well-engineered stereo or surround recording.

3. I owned the original 901 and have not heard the later versions. However, it
was not particularly clean, especially at high levels.

4. If you're going to equalize the drivers, wouldn't it have made more sense to
overdamp them, so that only a 6dB•/8ve boost (though admittedly over a wider
range) were required, as KLH did with their portables?

Along those lines... I owned a KLH Model 11 FM before I bought my first "good"
system, which included Bose 901s. My initial reaction in comparing the two was
that, overall, the 901s didn't represent any real improvement over the portable
in terms of transparency, detail, coloration, etc. Which shouldn't have been
surprising, as both used small full-range drivers (though from different
manufacturers, of course).