I've noticed that several languages of East Asia and the Pacific islands like Japanese, Chinese, and Hawaiian, have much stricter rules governing phonotactics than languages in other parts of the world.
Is this a legitimate trend, or have I just not been looking at the right languages?
And if it is legitimate, are there any possible reasons for it?
Recently, the World Phonotactics Database was launched. While I've noticed some errors in languages I'm familiar with, it may be useful to check there.
First off, is there a trend across languages in terms of syllable structure? To start with, let's look at how many consonants can be in an onset. Their sample contains 2,338 languages. Of these, 2 do not allow onsets, 1,363 allow for at most 1 consonant in their onset position, 727 allow for at most 2 onset consonants, 229 allow for at most 3 consonants, 15 allow for at most 4 consonants, and 2 allow for at most 6 consonants (note that they have no languages in their sample with at most 5 onset consonants).
Let's also look at how many consonants can be in a coda. They again sample from 2,338 languages. Of these, 485 languages do not allow for coda consonants, 1,373 allow for at most 1 coda consonant, 358 allow for at most 2 coda consonants, 107 allow for at most 3 coda consonants, 12 allow for at most 4 coda consonants, and 3 allow for at most 5 coda consonants.
With this in mind, I think it's likely that what we're seeing in the rest of the world--where "familiar" languages allow for complex onsets and codas--is actually a result confirmation bias. Indo-European languages, for instance, with the exception of highly divergent languages like English or Russian, really only allow for at most 2 or 3 onset consonants (2s include Armenian, Spanish, and Punjabi; and 3s include Albanian, Irish, and Lithuanian).
In most of the world's languages, a CV structure is preferred. This is, as far as I'm aware, a very old typological generalization. The Universals Archive cites Jakobson and Hale (1956) as the first statement of this structure being a linguistic universal.
The answer is you might be oversimplifying the facts. We have no data on Hawaiian or other ancient languages of Pacific phylum yet, but here are some points proving that at least Chinese and Japanese do not fall under the same category:
The Chinese is basically monosyllable, CV, V, Vc or CVc-structured language while Japanese is a polysyllabic, mora-structured language.
The Japanese used to have vowel harmony.
Some languages of the area (Thai, Burmese and tribal languages of China) have different prosodic structures, including C2C1V- initial syllables.
There are languages like Finnish or ancient Kretian sharing the same predominant CV- structure for syllable like Hawaiian or Japanese (although Hawaiianan word may also have +VV+ syllable structure), but this does not mean these languages are related by their syllable-structuring principles.
