i would agree that active has its advantages over passive crossovers, but as you pointed out not everyone is capable of setting them up properly and can experience dreadful results.
also you must note that if you have passive speakers already, YOU CANNOT DISABLE THE PASSIVE CROSSOVER BUILT INTO THE SPEAKER UNLESS YOU PHYSICALLY REMOVE IT. so if you are planning on doing an active crossover network before a passive speaker it is worthless, because the speaker will still cross the signal over again.
i have a lot of knowledge of audio, but i am not vain enough to say that i know how to design better speakers than major manufacturers, so ill stick with what ive got and what i am happy with. nor am i gonna run out and buy a bunch of new speakers.
the crossover inside of your speaker is optimized for its components, JUST LIKE THE WIRE INSIDE IS OPTOMIZED for its purpose, and while it may not be perfect it is good.
and remember that regardless of how perfect you think your system may be, it is still going to only sound as good as it was recorded or worse. ideally it would sound exactly like it was recorded, more than how you "want it to sound, or expect it to sound".
a lot of people love tube amps and there is a reason why, they produce a sound that you like to hear. is it 100% accurate (most of the time)?, no, but good and accurate are not always the same.