Mindscript has two distinct advantages over normal writing. One is that it does not require any training to read, so mindscript "literacy" is universal. This is important since most Locus denizens are illiterate in the traditional sense. The other is that its meaning is clear and constant regardless of the native tongue of the reader. This eliminates the need to translate its message into multiple languages.
Mindscript is most commonly used in signs and other forms of public writing, particularly in cosmopolitan locales where the native language of passerby cannot be taken for granted.
The main drawback of mindscript is that it is expensive to produce. Since creating mindscript requires magical training, mindscript "literacy" is highly asymmetrical; anyone can read, but very few can write. For this reason, quite a few people learn mundane script in order to keep records, write letters, or read books. Most guilds and trading companies keep extensive records in mundane script, a feat that would be grossly uneconomical if they had to hire wizards as accountants.