Sounds like it might make learning pronunciation less confusing?
I could see where that would be true for a native speaker, but damn, was it difficult for an American English speaker to get his head wrapped around it. Because to make it worse, ecery vowel has only one sound in Hawaiian - "A" is pronounced something like "ah", "E" is pronounced more like "eh", "I" is pronounced something like a long "E" ("see, be..."), "O" is "oh", and "U" is "uh".
Because each vowel is always only pronounced one way, they have to use combinations of vowels to make a lot of sounds that we just handle by pronouncing vowels differently in different words. For a long "I" sound, you use "ai", for a long "A" sound you use "ei" (but stilldistoinctly pronouncing both letters, albiet very subtly), and about a dozen other combinations like that.
I actualy did get pretty good at it while I was there, so maybe in a roundabout way it actually is an easier language to learn. Because I'm not good with languages. I guess the pronunciations are actually pretty simple to understand; the hard part is teaching your mouth to make those strange sounds, and memorizing how to combine the vowels.
Not to mention, remembering how many syllables there are in words like humuhumunukunukuapuaʻa.