Oracle Database Discussions

For anyone building a new system does it make sense to not use sequences at all and instead rely 100% on sys_guid?

As far as I can tell, sys_guid is superior:
1. It is guaranteed unique across all systems everywhere
2. It is faster than a seqence
3. Many of the restrictions on a sequence (like needing to use it in DML, not just calling it from PL/SQL) do not exist
4. Indexes on it should be better behaved (especially with RAC)

Are there any benefits to Sequences besides the marginal one of using less space?