Why not go crossover-less?

A well-accepted and desirable configuration! Most active speakers work exactgly that way.

Kal

But you lose flexibility, you have to chose the drivers and then design the crossover for them. You will not be able to use other speakers without modifying the crossover. This is why this approach, despite advantages, has never taken hold. Most audiophiles middle name is change and this renders it very difficult.

For bass xovers, particularly hi-pass, it really helps and usually adds flexibility but it also means biamping, one way or another. The payoff for mid/treble xover isn't as significant because the passive components are much smaller.

Could the following be another reason the cross-over is placed in the speaker? When the x-over is placed in the line stage is it more likely that errors will be more pronounced because of the amplification of any errors? We are hearing improvements to our systems when changing the speaker caps, which obviously means the caps are contributing their sonic signature. Will there ever be a sonic-less cap? Can line-stage cross-overs be made that influence the sound less?
I found the speaker that'll stay with me for a very long time, I also found which amp I will use to drive them. If a dedicated cross-over was to be designed knowing the input impedence of the amp and output of the preamp could the line stage cross-over outdo the other approach the speaker cross-over way?

A crossover in the line stage means using at least 2 amps, you can't feed 2 signals to the same amp.