Pro musicians in BAND....do not want or need an arranger...but that same musician if he/she were working by themselves and if they gave it a chance would love an arranger. I've had both...a Kurzweil K2600X and arrangers...for me I can do my 'thing' with an arranger and not a workstation.
Actaually...go listen to a few bands...do you even hear the keyboard player? NO, unless they are doing a solo (rare) or playing piano real loud. You sure do hear the drums, and distortion guitare, that is to drown out the singers in those bands so we don't hear that they can not sing! But they jump around a lot! If you want to hear some great keybords go listen to Bee Gees. They really value the Kurzweils they play.
As we know..the arrangers can also be used fine as a WS...just turn off the arranger and play full keyboard mode. But, why would a band guy pay more $$ for an arranger...not.
Remember the home Organ was the predesessor to the arranger, we left hand had accomanyment in the 1960's including drums. And it was good for that time. Or we used a sideman (drum machine).
It was Piano or Organ...now it's WS (or Piano) or arranger. Seems you are either a Apple or an Orange guy? (some are both)