I'll add Airfix, Monogram, and Lindberg to the list of companies that used to do it right.
I think the decline of the good old-fashioned instructions started with the growth of the hobby to international status. Back in the seventies, two things happened that had a profoud impact on how plastic kit companies did business. One was that Tamiya, Hasegawa, et al started making major headway in the American and British hobby business. Tamiya couldn't do much business in the U.S. or U.K. if it didn't include English translations of its instructions. (For a while, Japanese kits did get sold in the U.S. with only Japanese instructions. The hobby shops got loud complaints from customers.)
Also, the Canadian Parliament passed a law to the effect that all products sold in Canada had to be labeled in English and French. (There had been a lot of complaints from Canadians whose primary language was French.) The American manufacturers (Monogram, Revell, and the soon-to-be-extinct Aurora, for instance) looked hard for a way to comply with the Canadian law without packing their boxes with paperwork - which does, after all, cost money. The solution was to put the phrase "modele reduit" (scale model) somewhere on the lid of every kit, reduce the amount of text in the instructions to a bare minimum, and provide the few words left in both French and English. They figured out how to cut almost all the text out of the instructions. Instruction sheets became almost entirely pictorial, and such "unnecessary" items as parts lists and verbal directions fell by the wayside.
As the market broadened, the manufacturers figured out that they could save money by packing the same instructions in all their boxes - regardless of where the kits were going to be sold. (That made more sense than boxing some for the English-speaking market, some for the German, some for the Japanese, etc., etc.) And the trend continued.
I just took a look at the online instructions for the Revell Germany F-15 in 1/144 scale (a tiny kit with about 70 parts. The first page of the instruction booklet is devoted to a brief history of the real F-15, in English and German. Then comes a crowded page of "Before you start" general instructions - in 21 languages.Then a guide to the cryptic symbols used in the pictorial instruction diagrams. Then a list of paint colors (also in 21 languages). Then three pages of diagrams, replete with symbols but with nothing in writing. Then the color scheme diagram, also with no text. The whole thing comprises eight pages, only three of which actually tell the purchaser how to assemble the model.
From Revell Germany's standpoint, doing it that way makes sense. Imagine what that Mayflower kit would look like if all those fine old instructions were included - translated into 20 other languages. The instruction book wouldn't fit in the box.
I suspect that if you asked an executive at Revell (or Airfix, or Tamiya, or whoever) why his company doesn't pack better instructions in its kits, his answer would be "we can't afford to." Ideally, I suppose, Trumpeter would pack some of its HMS Dreadnought kits with Chinese instructions, some with Japanese ones, some with English ones, etc., etc. But there are some obvious drawbacks to such a practice.
I don't see the trend reversing itself. I'm afraid we have to reconcile ourselves to pictorial instructions.
One alternative does occur to me: put separate, single-language instructions on the web. In one of my other hobbies, classical music, recording companies are starting to do something like that. You can buy an opera on a couple of bargain-priced CDs, and download the libretto from the company's website. That saves the company the expense of printing the libretto, and makes it available to anybody who has a computer. (And the purchaser can print it out - a boon to aging, nearsighted music lovers like me, who have a horrible time reading a libretto that fits in a CD jewel box.)
How about it, Revell? Pack your cryptic, pictorial instructions in your kits, and offer the customer the choice of downloading some good text in German or English or Russian or Dutch or Spanish....
Only rarely do I run into a kit with any real text on its instructions. Eduard isn't bad (it actually names some the parts), but almost all the other companies have gone over to pictorial instructions.