I suspect Bruno that the dreaded word "fashion" has a lot to do with it. Home organs became fashionable in the 70's and 80's and like all such things in this modern world they have their time and then fade into the past.

Of course there are more serious factors like size and weight in the equation. I also think that the small army of manufacturers who flooded the market with rubbishy organs that quickly disapointed the purchasers had a lot to do with it.

Regards,
Trevor