Why so few speakers with Passive Radiators?

a passive radiator cost much more then a port

A passive radiator speaker may sound slow with a tube amplifier that has a low damping factor. Sealed speakers tightens up the bass by default. 

But, with an amplifier having a good damping factor? A passive radiated speaker can sound as tight as sealed,  but having more dynamics than a sealed can allow for at higher volumes.

As I look back on various speakers I've had over the years, the very best sound, particularly in lower registers, came from sealed designs. This was true with big living room speaker systems; and it's true in the last 2-3 powered monitor set-ups on my desktop/nearfield system. It's also true with subs, where I find sealed to sound best.

Yes, this assessment is 100% subjective; I've done no testing apart from whatever my ears reveal to me.

Currently in my desktop setup, I've just purchased a high-quality 2-way speaker, a sealed design, said to have particularly bass for a speaker this size (ATC SCM12 Pro). That, plus a class D amplifier recently purchased (strongly influenced by positive reviews/comments regarding its musicality) will be my first amp+passives experience on the desktop. I have high hopes. In the case of the ATC, not only do I expect cleaner/clearer/tighter bass than w/previous ported & powered monitors--but hope to also get some of the renowned ATC clarity & detail in the mids & highs (said to be accurate by not bright).

I was relatively interested in several powered studio monitors that feature passive radiators, but feel I might do better with audiophile passive designs (this ATC can be considered a hybrid--it's the professional version of their very similar "hifi" model, the SCM11 v2, but reviewers usually comment on its "musicality" (an extreme rarity in the pro world to see that word).

Wish me luck!

My first pair of what I consider to be good speakers were Klipsch kg 4.2. They have a 10 inch woofer and a 10 inch passive radiator and no port. They blew away my old pioneer 16 inch mush-woffer speakers with deep, tight, and powerful bass. They are definitely heavy on the bass.