Why HiFi manufacturers don't make active crossovers anymore?

"Midrange compression driver in the Uccello’s is the B&C DCM50, and the tweeter is the DE10 - also from B&C. The midrange horn is a "variation" of or slightly modified version of the Eliptrac 400 (the modification, to my knowledge, seems to entail the edge of the mouth of the horn, and how it meets the baffle here) and yes, it’s made of CNC’d, stacked birch plywood.

What’s the details of the bass horn you’re using with the 402 mids horn - does it sport a 15" driver, and how low is it tuned? Any thoughts on the 2" (exit) driver to use?"
  That DE10 is a super driver and the one I use on the MAHL tweeters I make. The bass horn uses the Klipsch K-43 woofer and is -10DB at 27hz and near full output as low as 31 DB.
  The 2" driver on the 402 is a Klipsch 1132. I am going to experiment with some 2" throat horns soon and thinking of B&C for those to since I am an OEM with them.
  The Crowns are nothing fancy and are xli800's.    A Xilica xp3060 is the brain behind it all.

miniDSP has some nice active crossovers for different price ranges, just found them in the last week. 

I also have good experience with custom made Linkwith crossovers via aliexpress. You can choose the frequency and upgrade the operating amps. I took Muse8900 this time, but before even the Muse02 from italy. Quality was really good to be honest! I have put it before two Nap200 going to B&W PM2. For this speakers clarity increased and I could play louder in biamping. 

For my Elac507 Biamping didnt work! I think the reason is that the impedance of Low and High is different themself. In Biamping mode i had far too much bass. First i didnt like the speaker. When stopped biamping te sound became a dream. So i am out of biamping :) just got a Primare A32 with 2x400 Watts at 4Ohm and all is perfect. The only thing I will do is to go on wi-wire for the High-channel. I tried that once with Kimber 4TC and the effect was nice for the mid and high range, but it was not my cable. 

I purchsed an ART 355 EQ whicj has high ratings. I have read people ising this on systems much more expensive than mine.  I was totally dissatisfied with what it did on my system.
1  compressed the sound no matter how it was adjusted
2. Soundstage disappeared.
It was not good.  
The only one I ever owned that did it all righr was an audio control c101.  

The two most important considerations for a stereo are your speakers and the room that they are in. Passive set ups don’t allow you to dial in the speaker room interaction like active crossovers do. That’s the real advantage in my opinion. I use REW with a high end microphone to analyze the room. I’m able to add 12 biquad filters to each channel with my mini DSP. The distortion tamed by this process is unbelievable and the sound improvements truly amazing. Most consumers don’t want to mess with the process but it only requires probably a day of messing around and then it’s set which people argue is a Sisyphean task and never ending. You need to add multiple amps as people have noted and have multiple subs to really make an active set up effective as most distortion and negative room interactions happen at lower octaves. 

I've used both fully active biamped (Snell Type A II Imp), passive biamped (Martin Logan Prodigy, with level adjustment for woofers), and regular passive systems.  In reality, every system with a subwoofer is a passive biamped system.
In general, if you have the ability to do the setup, I think a full active system will be superior. I knew a guy in the 80s with a full Levinson HQD setup: 3 way active biamp setup of Hartley woofers, stacked quads, Decca ribbon tweeters, 6 ML2 amps, 2 LNC2 xovers, 2 ML6 mono preamps. He was very capable and the sound was excellent.
That said, I will always observe the speaker maker's recommendations for slopes and use an RTA with pink noise for initial setup, tweaking afterwards for taste.
One aesthetic issue is the quality of the crossover.  Would you want to put in line, between the exotic amps and preamp, a $200 cheapo xover? Probably not.
The new DSP based xover systems, assuming excellent DACs, would be a great solution. You'll need a speaker system with access to the driver terminals and the ability to eliminate the passive elements from the signal path. The DEQx, while limited to PCM at 96K output, has SPDIF digital outs for each of the 3 xover output bands.  This means you can create as elaborate a digital system as you like: Streamer->DEQx->3 MSB select->6 MSB mono amps. Wow!