Sure, if an application uses an elevated installer -- but as you note, not all do. It does look like WER may support options being set in HKCU (per-user) as wel

Sure, if an application uses an elevated installer -- but as you note, not all do. It does look like WER may support options being set in HKCU (per-user) as well as HKLM (machine-wide), which would be a way of handling local installs. I wouldn't characterize Steam's world-writable folder strategy as smart, compared to a more secure model using an elevated downloader and installer. I fail to see what Office's title bar rendering has to do with its exception handling strategy. As for path length handling, Office also hosts a large in-process plugin ecosystem, so it has to be conservative with such application-level policy changes.