ASA was changed to ISO to get rid of the different rating systems that existed, and replace it with one.
The most well-known rating system that fell victim to this was DIN. ASA 100, DIN 21 should be marked as ISO 100/21. But the DIN part fell off very soon.
The change was also undertaken to get ISO certification in the photo industry for speeds, color balances, chemical purity, nomenclature and chemical handling, etc.... Kodak was up to ISO 900x certification at the plant for its various projects. It was rather wide sweeping and now includes image stability and testing methods.
ISO 9000 certification is quite another matter though.
It is not about setting industry standards, but about allowing a company to define what it thinks constitutes quality; let that company record those thoughts about what they themselves think they should do, in protocols that should be adhered to; and then audit their operation to see if they do indeed adhere to their own self-defined quality standards.
And if they do, they get an ISO 9000 mark of approval.
A marketing tool. Nothing more.
Well, it is more than that. Kodak was able to use this with suppliers and environmentalists to show their needs and compliance with certain laws. They could show Lead and Mercury emissions and give a supplier their requirements for photo grade chemicals. It also let the industry see what Kodak was doing and using.