Hi Suki...It's a COMMON Marketing practice of releasing New Products, Both Yamaha and Roland in Their Pro Synth Line of products,etc at Winter and Summer Namm Shows in The US...Korg Has Been a little different,Releasing about anytime.
Both Roland and Yamaha are VERY secretive on New arrivals...Think about it.Example:Roland Introduced the Newest G Series Synth...After the New MotifSX series was released...Quickly Yamaha had to put out an New OS to Include some things the Roland was offering!
We see the same thing happening now with the Arrangers. Korg soon releasing the OS2 to compete with Yamaha Tyros mega-voicing,etc.
We all have to remember reguardless what Keyboard we play competion makes them better...I firmly believe the Big three Do listen to a degree...If not they would not release OS updates.
I also believe at THIS time they FAVOR the European and Eastern Market simply because Arrangers are Generally Used More for Public Music,etc and accepted so much better in general.
As for here in the US....We have a long ways to go.It may never change...Rolands Marketing is next to None and what we have is shameful at best...(Europe, it's a little better)...Your BIG online stores like Sweetwater.com promote arrangers as writting tools for Studio work,etc.
I guess the Best thing Maybe is to Play what We like Best and fulfills our needs...Put the Joy of Music in Peoples Lives(So many need it now)...And try to Earn some extra money(We all could use That)and last but least be Thankful for what we have!