I think it is the fault of the keyboard salespeople and Manufactures that the Arranger Keyboards are thought less of than Pro instruments. There is a lot of technology that goes into making an arranger instrument. Unfortunately the arranger instrument is billed as, the one finger wonder with an intro and ending. "Look, you don't even really need to know how to play, to sound good with an arranger instrument" is what I hear from sales people and or customers. This may stem from the old organ days in the mall where a front pumper would seduce people into thinking that anyone can play in 5 mins or less. Most everyone would like to learn to play an instrument and feels that they have a song burning inside themselves waiting to be discovered and sales people and manufactures encourage this thought process.

This brings me to another problem, because for the untrained ear, some no talent can hit a couple of one finger notes and peck out a melody with the right hand, and sound to some as incredibly talented. Pros in a band feel threaten from an already shrinking market of live entertainment from DJ's, Karaoke, and Beat Mixers. So they discredit the power of the arrangers.

Although some professionals do use arranger keyboards, others just use them for writing and arranging, and use the live band when performing to keep the magic alive.

Last point and I think someone sort of hinted on this already. There are more wannabies and hobbyist than actual working musicians, so there is a reason that manufactures target this audience. When you use the name Pro keyboard to a novice, you scare them into thinking it is only for professionals, visa versa, you will never scare a professional by calling in a home keyboard if it sounds good and gets the job done and gets em a check.