libtomcrypt is a _great_ library.  That is what hashlib uses for the hash algorithms when OpenSSL is not available.

But the _primary_ reason for using OpenSSL is that it is the defacto open source location for the best architecture specific implementations of any hash and crypto algorithm.  OpenSSL outperforms libtomcrypt by a significant factor (easily 2x) in most cases.

The NSS everywhere effort mentioned in the fedora link sounds interesting.  I support having the ability to link against that instead of OpenSSL or copies of libtomcrypt but I am generally in favor of absolute performance per byte of all algorithms concerned being available.  (ie: don't force hashlib to stop using openssl, just provide an alternative).