From what's been said, it seems like it was made to be updated so that Apple could easily issue security updates. They've already increased the delay between re

From what's been said, it seems like it was made to be updated so that Apple could easily issue security updates. They've already increased the delay between repeated attempts at password entry. Probably they were worried about vulnerabilities or bugs that hadn't been found and wanted to maintain debugging connections to make repairs easier. A tamper-resistant self-destruct mechanism with no possibility of recovery introduces extra points of failure, and it seems that until now, they didn't think it was necessary. Look at the controversy over the phone not booting with third-party fingerprint reader repairs as an example. People were upset when they found out that having their device worked on could make it unbootable, but Apple was able to easily fix it with a software update. If it had been designed more securely, it might have wiped data when it detected unauthorized modifications, which would have meant even more upset people. Now that this has become a public debate, there will be a very different response to making it more secure.