I think it's to make a clean break. The true full synax of C is horrendous and has 1000 edge cases that nobody is aware of until you have to write a C compiler. If you're making a new language, you're not going to support all that. But which subset do you support? Whichever subset you choose, you'll violate someone's expectations, because they thought it was like C.

By breaking with C syntax completely, you can start without expectations.