HIPAA contains a security and privacy rule, but its original aim was to spur patient record portability between providers and insurers. That lineage of regulation, which also includes HITECH, ARRA, and provisions tied to Medicare expansion, established the carrots and sticks thought necessary to modernize the health industries records--to get them off paper and into bits. All this modernization eventually happened, but it's hard to say whether the regulation was the primary driver or if these companies would have done it anyway. Having worked in the industry, I lean toward the regulations being the primary driver. Low risk tolerance was already a characteristic of health organizations before HIPAA (and I think patient safety was the main reason). When HIPAA was signed in 1996, most US industries were heavily computerized, but health organizations lagged far behind. Lack of competition where most providers and insurers operated meant there was little commercial incentive for them to spend money to be able to exchange files with organizations in other states. Digitalization just wasn't coming together in health care as rapidly as in other industries, although I didn't work in health at the time so I don't feel like I personally know all the reasons.
It's been a long time since 1996, but most of the IT messes inside health organizations are self-inflicted. HIPAA and friends don't mandate which operating systems you use, specify approved encryption algorithms, or tell you when and how to update your computer systems. These are all choices left to the implementation teams, and they chose to work with vendors who aligned their solutions to information architectures that just don't change very fast. I think if you compared this IT situation to, say, large scale manufacturing in the US you'd find similar problems of outdated platforms supporting expensive and hard-to-change niche software. And it's probably market forces, not government regulation, that's responsible for this similarity.