yea the restrictions are pretty rigorous, but that doesn't inhibit creativity.
Its just the beauty and genius of carnatic that there are so many raagas with so many restrictions but each can be improvised completely.
its like this: a child who learns some words in a language can construct several sentences in that language using those words, which may all be good.
another student may learn complex structures in that language such as active speech/passive speech, complex, compound sentences and loads of stuff, and use this to construct a poem. A poem may be all in passive speech and sound beautiful and unrestricted. But it will definitely have more cohesiveness and structure and overall beauty and harmony, than a poem which mixed up passive and active speech. So more restrictions might result in maintaining harmony without restricting creativity.
Aadalaam Vaa, Paadalaam Vaa, Kondaadalaam Vaa
Engum Endrum Pongidudhe Inbam, Inbam Pozhiyude