So what do we do?


We develop standard, well-known, cryptosystems with keys sizes ranging between 128 and 256 bits.  We hope it's strong.

We call this standard AES (a.k.a. Rijndael).

This was done over the last few years, and it's finished now.

It does basically everything we might want in a symmetric cipher.
So there's no reason to make any others for a long time, except maybe for extremely specialized applications