My impression is that horns are a bit more popular these days than in the recent past, but then most things tend to cycle in and out of fashion, irrespective of whether they are good, bad or indifferent.
Horns have their strengths, but they also have weaknesses. In other words, they are like any other speaker or piece of equipment. The key to audio happiness is to line up the strengths of a speaker with the those areas where your ear is most sensitive or that you find important in sound reproduction. In my case, while I enjoy the dynamics of a good horn, I've never heard one yet that didn't have a distinct honkiness that knocked it out of consideration for me. It is a sonic trait that I am apparently more sensitive to than others.
Interestingly, I've just finished the book "Musicophilia" by Dr. Oliver Sacks. It talks about about the brain and how we perceive and process music along with the manner in which afflictions can affect our hearing music, or even using music as treatment. While the book says virtually nothing about audio equipment, the entire text reinforces how differently each of us perceives music. Some of this comes how our brain is wired from before we are born, some comes from experiences and training as an infant (which permanently affects how connections in our brain form) and some comes from our training and experiences later on. (A very interesting read if you like that kind of stuff.)
The net result is that each of us is going to be impressed by different things when we listen. Therefore, rather than read about how this or that speaker is the best thing since sliced bread, the key is to get out and listen and find out what [i]you[/i] are sensitive to when listening to music.