Do you have a list of the games you worked on?
I understand that these ports were often cash grabs. The original Japanese publisher could sign away the home computer rights to one of their games and get a nice check in return.
But, still.
Surely the original owners of these properties must have realized that by providing at least some assistance to their licensees (something requiring almost no effort) they would see better results?
Surely these Japanese publishers must have understood that a bad port of Outrun or some other game would reflect badly on them and tarnish their brand even if they had no involvement in it?
I say this as a long-time fan of Sega and other Japanese game companies, which were filled with some brilliant folks. That's why these decisions have always baffled me.
There weren't standard digital art tools in the early 80's. Things may have been physically drawn on graph paper, manually converted to binary, and then the drawings disposed of or otherwise inaccessible due to things like contracting situations, etc.
A lot of those design materials were indeed saved, btw. This book and its sequel collect a lot of them:
https://www.forbes.com/sites/olliebarder/2014/11/12/the-unto...
At that point, the developer walked off with money, and the publisher walked off with a game binary they could resell and market however they liked (including taking the IP rights and licensing them to a porter.) But the publisher didn't retain any right to the developer's time; and often, the "developer" was just some college kid who developed just the one game, moved on to other pursuits, and now can't be found.