Many of you know It’s my contention ALL SPEAKERS should have Level Controls, to refine their frequency distribution in your space at your positioning in that space, and re-adjust for any space you move/use them in.
L-Pads retain impedance shown to the crossover; Potentiometers alter what is shown to the crossover a bit.
While I agree that speakers benefit from being able to be altered for different placements and rooms I disagree that L-pads or even switched R arrays in a passive speaker are desirable. They are crap for reliability. Professional, active speakers have these features and IMHO are the correct way to implement them.
Also, adjusting individual drivers is not really as good of an option for adjusting the output as having an upstream EQ or tone control. In general, the crossover points of a speaker and the human hearing and studio choices may or may not match up. The "loudness" button on my receiver will work correctly regardless of the speaker design. I'd hate to try to achieve the same thing with a set of level controls on a 2 or 3-way speaker.