Care to elaborate? I was thinking the same thing, all the vowels have a logical symbol in the pattern, as opposed to something unique or more striking.
If you look at dotsies.org you'll see capital letters have smaller dots above them to distinguish them from lower case.
Using a pattern was done to make it easier to learn, but many options (with patters and without) were tried out and rejected. Notice that the vowels all have dots at the top row or bottom, which is desirable as it tends to give words hollow shapes with negative space in them.
Optimizing for space efficiency has many dimensions, too dense is not good, and too sparse is not good. There were a couple versions where the frequent letters had fewer dots and were concentrated toward the bottom, but that increased possible ambiguity between words one might mistake for being shifted up or down one dot.
The problem with using the dots as a denotation for vowels is that that kills of any way to deal with diacritics, let alone any of the latin-1 supplement characters necessary for languages other than english.
That all not considering the lack of baseline etc. Also, why is "z" the only letter with a 2-dot-width?
My computer screen gets dirty. At first I thought the small dot over the capital was a speck on my display. I tried to rub it off.
I came up with this line last year: "I took a polish to the Polish readings in Reading by the nice guy from Nice." I still haven't found a word which describes two words which are spelled the same except for capitalization and which sound different.
