The importers have to sell a product. This means that it must be appealing. Bachmann, BLI, MTH, Athearn Genesis, Hornby/Rivarossi, Trix, Kato, Blackstone, and soon Rapido, all produce quantities of steam that these days seems to sell well by subscription (meaning strictly limited production), or as in the case of Bachmann, MTH, and Kato, they build 'em and let them sell as and when they do. These importers can't sell locomotives than few people can use, let alone lust after and place an order. Nobody is going to pay $269 for a sound-equipped BLI steamer knowing that they'll have to put it on the mantel to enjoy it below their large flat screen TV. People want to see them run. Given that, even today with larger homes, most of us have to live with curves with radii downward of 24", our importers have to know their prospective clientele. They have to seduce them. One way is to engineer their products to have both a selling price and a selling functionality. With those two factors filled, people feel they can buy them. When you consider that so many brass locomotives, those with prices back in the 80's that were in the $400-500 range, needed a lot of both tweaking and maintenance, and you compare that with what we get for what in deflated dollars would equate to about $120 back then, we're doing very nicely...thanks very much.
Bottom line, these are toys that must sell...or our friends go broke and seek other work. So that they sell, they make engineering compromises, including the foobie articulation. When I compare the toy trains of John Armstrong's day with what I can get for somewhat less in today's dollars, including sound, DCC capability, and much better detailing and tooling...it's a cakewalk.
Are diesels more prevalent and do they outsell steamers by about three to one? U betcha. They must. It's basic economics which, after all, is a social science. It's all that today's interested players see, and except for the odd steam encounter, it's all that moves both them, emotionally, and their various goods that the entire family needs to live.