Donny... It's boring until you learn how to do it... then it is a lifetime of enjoyment!

But the main reason to learn it, like anything else, is to broaden your choices of how you play. Just as learning the guitar improves your ability to emulate it well, or playing a horn helps with your lines and phrasing on the arranger, learning the piano helps you play pianistically, when you need to do it..!

You've often mentioned you don't like to use sustain pedals... But you really can't play piano properly without one (you can say otherwise, but all you are doing is choosing passages that CAN be played without one, not playing anything you want), and learning the piano will give you a big leg up on that.

The minute you cut yourself off from a whole sector of keyboard types (and, TBH, the largest and most influential sector, at that!) you start to limit yourself.

Not to mention, the increased workload for the LH (lets face it, accordion and arranger playing hardly gives the LH much of a workout!) of playing full piano parts makes a radical difference in what you can do on a keyboard. Much is made of the transition that accordion players make to arrangers, but I believe this is primarily because you simply have moved from one type of keyboard that under-uses the LH to another! But start using MP3's, loops, or SMF's, take away the need to do simple changes with your LH, and you can really start to USE that LH!

I have always tried to develop a style that was TWO RH's, not a RH and a lesser LH. That way, both hands can play something quite important to the piece, and remove the need for more automatic playing, but I really doubt I would have ever been able to do this without having studied piano... Nothing else really works your LH the way the piano does!

Certainly not an arranger!