The point is to transcend...
So let's review what we know about the bija mantras:
There are several uses of bija mantras: for purification, acquisition, propitiation, or in some cases for protection. But, the most noble use is for spontaneous transcending meditation.
Vedic "mantras" are Sanskrit words found in the Vedas. However, "bija" mantras are just seed sounds. They are not "meaningless" sounds; everything in the cosmos has meaning. But, bija mantras are non-semantic sounds - they are not words found in any standard Sanskrit lexicon.
Bija mantras, by definition, are esoteric sound vibrations; bijas are not words. The Sanskrit word "man" comes from the root mind, and "tra", a tool. Bija mantras are simply sound tools for thinking.
Sri Vidya consists of 'indestructible seed' syllables rather than words, so the bijas transcend such mundane considerations as semantic meaning.
Accordingly, a bija-only mantra meditation is not merely esoteric but
Seed-syllables (bijasaras) are the purest form of mantra. They do not make a request or praise a God, it is God's purest expression of Being.
According to Brooks, the Gayatri cannot match Sri Vidya bijas because it is still in common language; it is Veda and mantra, but when transformed into the Sri Vidya bijas "it's greatness increases."
The texts and traditions of Srividya Sakta Tantrism in South India
by Douglas Renfrew Brooks