Bradshaw, I agree with you. That said, while it could be profitable as a niche industry to have an Endo-Steel production facility, the start-up costs are massive: if your system doesn't have an existing orbital facility (and most Inner Sphere systems do not), then you have to build one, then you have to lift a bunch of materials and personnel up to the facility, etc. The result is a product that is four times as expensive as the best high-tensile steel available, and it is FAR bulkier as well, with the major benefit being that it is lighter weight -- and only really practical for use in Mechs. Not vehicles, not battle-armor, not dropships or aerospace fighters or jumpships, not civil engineering or building infrastructure or wide-scale commercial applications... only 'Mechs.
Given that bulk costs money to transport as well as weight, plus the tremendous start-up costs, I don't see how most legacy industries would want to develop Endo-Steel production on their own. I mean, it looks basically like the Fiberglass vs Metal debate on cars -- but what if fiberglass wasn't just more expensive and harder to repair and replace, but also SIGNIFICANTLY bulkier -- and with massive start-up costs that were much much higher than traditional steel or aluminum (which are not all that cheap in terms of smelting facilities IRL)? Who would want fiberglass bodied cars then? It would be (at best) a really niche/luxury industry.
That said, by the 3060s, a lot of armaments firms have Endo-Steel production, because the logic of Endo-Steel frames for 'Mechs is so clear: it's superior to Ferro-Fibrous Armor in terms of weight savings, and massively cheaper in terms of cost, both short and long term. It's one of the most cost-effective weight savings you can apply to a 'Mech, after double heat sinks. And if you can get your star empire to subsidize the orbital facilities, then the initial start-up costs are covered, too. Obviously the Mech-obsessed Clans use Endo-Steel in virtually all of their 'Mech designs, and have gotten the bulk way, way down as well.
Also in the Inner Sphere, you've got development of less bulky options, like Composite (3061) and Endo-Composite (3067), which are perfectly fine, but not always ideal for heavy and assault 'Mechs because (a) fragile, or (b) not as efficient. I know that Game Logic decrees that Clan Endosteel is just better, but it's always been a bit mysterious to me why the Inner Sphere doesn't just steal the technique and make Clan-grade materials.
See the story of how Andrew Carnegie basically stole the British Bessemer Steel process and became a monstrously wealthy monopolist.
