My theory is that it is related to nicotine content and addiction. Not saying that to throw a grenade in this thread, so please keep it peaceful if you disagree.
I just happen to suspect it's how it goes and there is nothing wrong with it. Assuming you're OK with being addicted to nicotine, which many of us seem to be. Keep in mind, not everyone here is a nicotine addict, as some are quick to point out. Disclaimer over.
I have the impression that a lot of newer pipe smokers eventually find latakia and have that "this is it!" moment. They've found that "real" tobacco taste and go whole hog for awhile. It is a uniquely interesting taste that a lot of new pipe smokers seem to discover in a uniquely similar way. Not everyone... but many. In nicotine content, latakia tends to be a step up from burley/cavendish blends... which happen to be the base of many aromatics that people (not everyone, of course) often start with.
With nicotine (addiction), the trend is to want more. It's usually subconscious, as most addiction is, but it's the general direction these things go. Alcohol, heroin, cocaine, etc. Eventually, you're taking a dose that would have killed you if you started there. Latakia doesn't have that bell ringing dose compared to other leaf that people "graduate" to.
So it then seems that a lot of people (not everyone) slowly (or quickly) trend toward favoring higher nicotine blends; particularly virginia/perique blends (perique is a high nicotine leaf) or dark fired kentucky (possibly the king daddy of nicotine content). Those are very popular components among committed (though not always addicted) pipe smokers who have been at it long enough to work their way through the major blend families... all the while building nicotine tolerance and needing a higher dose for that certain satisfaction that comes from pipe smoking.
Obviously this does not apply to those on board who are free of nicotine addiction. But for the rest of the junkies, I suspect that is why latakia eventually seems to fall out of favor.
It's all a bunch of bullshit, most likely, but it's the beginning of my theory. It makes sense on the back of the napkin I have here, but the math is very complicated and I'll not bore you all with the calculations.