A few points:

• Though "Hash problem" is barely more descriptive than node titles such as "hash", it is a lot better for the 'Search' (find) function.
• Concerns over the notion of "enforcing" multi-word titles are moot: 90% of the time nowadays when someone posts a single-word title, it gets considered by moderators, and fixed by Janitors. So the enforcement is happening already. Proposals that single-word node titles be rejected are not a new enforcement, they're an automated pre-emptive inforcement of what the Janitors are already finding themselves enforcing regularly.

I prefer that the course of action not be to put in place dummy-proofing, but rather to put in place additional warnings or help. To the right of the Title box, the following statement:

Titles concisely describe the topic of the node. Single-word titles are discouraged. See How do I compose an effective node title?

This and other helpful hints could be set up to be disabled via User settings after passing level 3, for example (that's an arbitrary level number, but a startingpoint for discussion).