Why was the RfC a poor fit for handling new requirements before 7.2, and what awkward workarounds did people use?

The RfC was designed for production support (break/fix) — it didn't fit a requirements flow.

Pre-7.2 there was no best-practice option, only workarounds: upload requirements as a Word document-type to a SOLAR01 project, or copy SMCR and reconfigure. 7.2's Requirements Management introduced two integrated processes (also integrated with ChaRM) to let IT + business plan/scope new functionality before implementation.