In addition to your point, being able to use, for example, Wireshark to debug HTTP communications is often handy. HTTPS makes that challenging.
But specifically about your point, when one audits an HTTP/1.0 client, should one also audit the TCP/IP stack in the kernel? I don't think most researchers/engineers would, and would (for sake of practicality) instead trust the underlying systems. Eventually, TLS will be thrown into that "underlying systems" bin. That time is not likely at hand; there are still too many shortcomings of TLS and its surrounding infrastructure. As evidenced at least by the OP. But when the time does come, writing an HTTPS client in a weekend will be just as practical, since you'll trust the software libraries/kernel to handle TLS. Just as you trust your libraries/kernel to handle TCP/IP today.
But specifically about your point, when one audits an HTTP/1.0 client, should one also audit the TCP/IP stack in the kernel? I don't think most researchers/engineers would, and would (for sake of practicality) instead trust the underlying systems. Eventually, TLS will be thrown into that "underlying systems" bin. That time is not likely at hand; there are still too many shortcomings of TLS and its surrounding infrastructure. As evidenced at least by the OP. But when the time does come, writing an HTTPS client in a weekend will be just as practical, since you'll trust the software libraries/kernel to handle TLS. Just as you trust your libraries/kernel to handle TCP/IP today.