I used to eat them all the time -- and yeah they taste pretty bad. I'm the kinda guy that says flavor be damned, if I just need a quick source of protein.
They're usually sold in convenience stores quite cheaply as otsumami (booze food). Since I'm now engaged to health-food buff, the last time I reached for one, I was told to look at the ingredients list -- which was a mile long. The commonly sold variety just ain't that healthy.
As the Japanese economy took off a more western style diet was adopted, with a stronger focus on meat. As well sausages are typically lower quality/cheaper protein so an increase in wealth would correspond with a move away from sausages.
