With all due respect have you ever seen someone from Osaka speaking to someone from Tokyo? There are frequent miscommunications and long pauses as people try to figure out what has just been said, and often these are matters of prosodic features rather than differences in dialect.

I've been to Osaka with native speakers from literally the neighbouring prefecture, and they bitched the whole way home about people from Osaka being hard to understand. ... that and the fact that people in Osaka ride their bicycles like maniacs.

So, again, with all due respect, I think you're severely over-estimating the role of consistency in pitch in mitigating misunderstandings.

While it may be true that a consistent pitch pattern may help to mitigate misunderstandings in a very, very small number of cases where context doesn't immediately make the meaning clear it also increases the learner's workload by at least an order of magnitude - for something that will only be useful in a very small number of cases.

An anecdote might serve to illustrate how important context is in Japanese. For a few years I worked in a Japanese school, and I had a really hard time reading the blackboard where they wrote the daily notices. For the longest time I thought I just sucked at reading kanji (which, to be fair, was part of the problem).

However I eventually discovered that a bigger part of the problem was that many of the teachers were literally not writing the whole kanji just the "essential" strokes that would make the meaning clear to a native speaker, and were omitting several of the smaller more fiddly marks (which are hard to make on a blackboard with chalk when you are in a rush).

This was such a normal practice that when I eventually realised it and told one of my co-workers her response was simply, "Oh. Yes. Sports coaches ne?" (the sports teachers were prime offenders when doing this, but a lot of other teachers did it).

What my anecdote is meant to illustrate is that Japanese is quite minimalist in its approach to communication. Often an exchange is just a series of short utterances where context is supplying the bulk of the informational content. The importance of being aware of context, subtle clues in the person's body language, and other environmental factors is far more important to communication in Japanese than precise variations in pitch.

Context is key to a degree that most English speakers trying to learn the language outside of Japan simply cannot grasp. Yet one rarely sees people posting on the subject of body language and the all-important "空気を読みます" (reading the air/reading the context). As far as communication goes in Japanese this is a far more valuable skill to learn, and will resolve ambiguity in a far wider range of cases than spending an inordinate amount of time in memorizing pitch patterns in order to obtain a consistent pitch that will only be useful in resolving ambiguity in a vanishingly small number of cases and which can be resolved far more easily by merely making more careful word choices.