Ha! Great post, Chas.
I distinctly remembering one of the more curmudgeonly of the older bunch (meaning around my age of 64) I jam with, referring to the arranger keyboard as the "blow-up doll" or "inflatable Love Companion" of the keyboard world.

Of course, he was also of the opinion that any amp that wasn't a vintage Fender Twin, a guitar that didn't have Stratocaster on the headstock, or an organ without the name HAMMOND between the upper and lower decks, should be relegated to pawn shops and city dumps.
I must say, however, that I really enjoy using my arranger (a Tyros4), and although I live alone at present, I also haven't found the need for "inflatable toys", unless you want to count the Yellow Rubber Ducky tucked away on the rim of my bathtub...you know, the one that Ernie, of Bert and Ernie (Sesame Street fame) always sings about "Rubber Ducky, you're the one...you make bath time so much fun".

Luckily for me, I have managed to remain in with a group of semi-retired/retired musicians that like to jam a few times a month and, except for Mr. Curmudgeon above, are quite happy (and perhaps a tad more open-minded) to play along with the auto accompaniments as long as it doesn't become a habit and the chord progressions aren't insulting.
I also play a really well kept B-3/Leslie 122, which my Tyros4 usually sits on top of...I often use the latter for Rhodes and other sounds.
I still regard my Tyros4 as a "tool". I feel, like any other electronic instrument or keyboard, it really depends on the skill and creativity of the player to make the most of it.
For my use, an arranger is both a "live" performance, and a recording instrument (most arrangers are basically self contained studios).
You can use the arranger as an educational tool, giving yourself access to the inner workings of a multitude of styles and genres, which will certainly increase your value and longevity as a working musician.
In music, especially nowadays, the more versatile you are, the more you work and a good professional arranger keyboard can keep you in the game.
For composers who have to produce music quickly in a given style that they may not be familiar with, an arranger can be the difference between making the deadline or losing the gig, and, actually, in most cases, people who hire composers don't care how you come up with the music, as long as you do.
Because of this, arrangers are showing up in the studios where their tracks are directly recorded from the arranger and put on CD for release. Of course, that makes sense, since the styles and performances are created and performed by world-class musicians.
Plus, you can edit styles to further personalize your music.
So, if you will, I can see both sides of the situation, but, for now, the advantages of having and using an arranger far outweigh those from not having it.
Again, great post, Chas...very thought provoking.
Ian