I have to side with Gary and Deane on this. Having played a great deal of western European music in recent years ,even the younger European folks still celebrate the music of their heritage, right along with their techno thumping.
Workstations satisfy the needs of those who don't do so, especially in the US and UK. An arranger is not needed when house/dance music is not much more than loops that are provided in WS's. And they don't need the sounds or styles in arrangers, nor do they need 4 variations of each and multiple intros/endings. We, the elders, use arrangers for OUR type of music and dancing etc. From a company's standpoint, why modify arrangers instead of just dropping them and letting the synth/workstations/controllers take over, continuing to do what they are doing now? Because we don't want to see arrangers die off? If you don't need what an arranger does, there are these other things out there that are sufficient. Ask any GC that sells to today's youth , and they'll tell you the biggest sales are in controllers with software packages now. No onboard anything. Everything comes from a vst on an ipad or laptop. The stores have entry level arrangers to start some kids off, then it's on to the other stuff, or not. Listening whenever and wherever you want from your mp3 player or phone beats dragging out an instrument for most kids. Technology, and today's taste, are leaving us in the dust.
And like Gary says, today's youth doesn't want to put the time into being real musicians. It is a generational thing. A lot of us learned how to play a piano because there was one in the house when we grew up. Don't see much of that lately. And I agree with the "instant gratification" theory too. While we were lucky to have all 6 strings on our first guitars, today's kids start with a guitar (which mommy and daddy spent multiple car payments on) , then get bored, and move on to the next thing until they are bored with that....
But adding things to arrangers that are already present in WS's and controllers w/vst's simply isn't necessary in a manufacturer's view, just for the sake of keeping arrangers alive. It would be simply non-profitable duplication to dump the old stuff and replace it with new.. The features that arrangers offer are tailored toward "our" generation(s) and are simply not needed for "modern" music. Arrangers suit our demographic much more than that of our kids or grandkids ,just as organs and pianos did for our parents.