Kronos's soundset will be extensively integrated. Also, it will have an extensive library of good, USABLE arpeggios and loops.
CONTENT isn't just styles. Content is the sounds, and how well ALL of them work together. In the case of modern WS's, the included arps are directly equivalent to the styles that come with arrangers as well.
CONTENT basically means, you open the box, and you start playing. Can you make great music straight away, or do you have to run off to the VSTi store, purchase several different products from different manufacturers, and then spend days, months, maybe YEARS trying to integrate them all so they work well with each other..?
As I tried to point out, balancing and integrating an entire soundset from disparate sources is an art form. VERY highly talented people at the majors do all this for you. You aren't constantly grabbing volume sliders, EQ shelves, dynamics adjustments and MIDI velocity and aftertouch curves to get them all to 'sit' well together in a mix. That work is already done. What's that worth to you?
Me, I'd rather spend weeks (months, years!) MAKING MUSIC, than preparing a keyboard so that it can (if I'm even talented enough to succeed)...
Yes, you can ADD more to a well set up, integrated keyboard (either arranger or WS) at your discretion. But no major makes you go through this step BEFORE you can make good music. And dominate the market because of it. Few keyboards are sold to sound designers. They are sold to MUSICIANS. And trust me, those are NOT the same skill sets..!
_________________________
An arranger is just a tool. What matters is what you build with it..!