Why not more popular?

Tech moves fast. Many audiophiles tend to have brand biases. Personal experience varies a lot. Most companies can stick to more conventional designs and still make a healthy profit. Most people don't listen to speakers anyway...they listen to music.

That Sony boom-box from years ago is playing as background music. Most folks don't sit down in 1 spot to listen to speakers. The other factor is competition among more well-known brands. Either people like it or they hate it.

mastering92, Ouch! Now there's an inevitable reality.

Welcome. 
So, If you're here I'm guessing your not just listening to a pair of Yamaha HS's? 

I recently bought some well-regarded OB speakers with a return period. After a couple weeks, back they went. Just did not like the sound--not enough flesh and weight. OB fanboys may say it’s because my taste has been corrupted by old tech and nostalgia. Really, they just did not make me want to keep listening. To each their own.

The wheel has come round once more. Open baffle seems to be enjoying a little flash in the pan status these days. It is easy to see why. First, they weren't made for a long time. Someone is always looking for the next shiny new thing, and if it hasn't been around in a while it can seem new even when it isn't.  

Open baffle is basically a version of what Martin Logan has been making for years. They should take advantage of the current rage and make an open baffle model. Oh wait, they are already open baffle? Whatever. Don't disturb the audiophiles while they are sleeping, they wake up all cranky and pedantic. 

I've never heard port huffing or weird boxy resonances but maybe that's because I only bother with the good stuff regardless of design. There is of course no magic involved in open baffle. The baffle is not immune to vibration and resonance. Your ears just aren't familiar with the set of resonances peculiar to open baffle designs. Yet. Keep listening. They will be. 

And that is what keeps the wheel turning.