I understand that some people prefer to do the editing and sequencing on the computer and that's fine. But it makes no logical sense to remove a function that a lot of musicians require for immediacy in terms of editing and sequencing on board the keyboard it costs virtually nothing extra . Some people don't want to have two keyboards, one for the studio and one for performing. It makes no sense to me anyway.
To the pro it does seem illogical, however, as pro use of an arranger is miniscule in comparison to the home user, (Which is what arrangers were designed for, as there basically just advanced versions of the old easy play features that were added to organs) so it is quite logical, the main reason Korg (And to a certain extent Roland) have more advanced features, is because they never had a dedicated home and pro user department, so in the beginning everything was just a dumbed down version of their pro keyboards, (Contrast this with Yamaha who have always had separate departments for home and pro) hence the reason that for quite a number of years a lot of users found them intimidating compared to Yamaha. (And also Technics)
Simple really
Bill