>Because the buttons were easier to build, until someone realised that
>the keyboard would be easier to play?

I believe you're on to one thing, and off on the other...

The button-box is certainly easier to build. It has less than
half the reeds (being diatonic) to get in the space and of
course half the valves, levers, springs, and other fiddly
bits.

However, I don't believe 'easier to play' is the case.

And I've played both.

The button box has an initial learning curve, but like a
harmonica or Anglo concertina renders acceptable folk or
traditional music within a short period of time and with
little knowledge of music theory. It tends to put the
player in the key intended by the makers and coordination
of the left and right hands is nearly automatic, once one
figures things out.

It's light, small, and within its limitations, quite useful.

The piano accordion, even in its simpler forms, is a lot more
intimidating. On average it's three times as heavy and twice
as large as the button box. The untrained musician sees nothing
but a sea of black and white keys on the right and black
buttons on the left. The size and weight of the left side make
bellows-control a whole new issue. It's very easy for everything
to sound like a dirge. Even for someone trained on piano, the
size of the keys makes for fingering anomalies. Unlike the button
box, you have to again start thinking about sharps and flats and
scales, and an octave on that instrument covers about twice
the space versus the four buttons of a button box.

I play a row-crossing technique on a D/G (usually) button box,
and I *still* find that easier (i.e, less effort) than navigating
the keyboards of a 120-bass piano accordion and managing all of
that weight and size.

When I started in squeezeboxes, it was with English concertina
and piano accordion. Being a classically trained pianist who
transitioned into ragtime during the Scott Joplin craze, I thought
that it would be the logical choice.

It wasn't.

I picked up button accordion out of necessity (participation in a
Dickens Faire where piano accordions were considered anachronistic
and thus prohibited) and being forced to figure out the D/G box
ranks as one of the best things that ever happened to me musically.

I think the piano accordion is initially 'easier' for a 'trained
musician' but for tranditional or folk music any initial advantage
disappears once a rather quick understanding of the diatonic system
is impressed into the neurons. The piano accordion appeals
intellectually; viscerally, buttons perhaps work better.

Now for the sailor picking something up to take to sea in order
to make some noise, the button box was just the thing. Very
easy to learn to honk out tunes, much less to go wrong, and
much easier to store under (or in) your bunk.

I tell people that 'the button accordion was the Casio keyboard
of the late 1800's.'