Someone has to control the crossover point. As you pointed out above, it can be convenient to have the option in a preamp, but it's also more circuitry that could be done better with a separate component or within the speaker itself. I don't see any sense in which it is wrong, and certainly there are some situations/gear in which it could sound better than not using it. If not, why would they ever have put in the feature.
Hell, if you really want to control the crossover you can put a Pass Labs XVR1 after your preamp, buy the gear to biamp/triamp and then pull all the inductors/caps/resistors out of your speaker and connect your amps directly to the drivers. That'd probably sound better once you find all the correct crossover values and levels, but it would potentially double the cost of your system and you'd have to spend many many hours working with the XVR settings. A first order crossover? Second? Fourth? How many poles do you want in your LP filter? Plenty of people do that, but they're mostly over on DIYAudio, not here on Agon.
Hell, if you really want to control the crossover you can put a Pass Labs XVR1 after your preamp, buy the gear to biamp/triamp and then pull all the inductors/caps/resistors out of your speaker and connect your amps directly to the drivers. That'd probably sound better once you find all the correct crossover values and levels, but it would potentially double the cost of your system and you'd have to spend many many hours working with the XVR settings. A first order crossover? Second? Fourth? How many poles do you want in your LP filter? Plenty of people do that, but they're mostly over on DIYAudio, not here on Agon.