Policies are a good thing to manage your SQL Farm with as you get the benefit of being able to control everything from a central location and you can prompt any policy changes to be applied to all servers, instead of having to manually update each one.
Manageability and time-savings are probably the primary reason for introducing a central management console.
As for a central maintenance plan, if you're just talking about running a job which carries out backups and reindexes etc on remote PC's, then the only real benefit is that you should have a uniform solution for all servers, meaning there is a lesser likelihood that something will be missed on one or run differently on one. And as above, a single update required, meaning manageability and time-saving are factors.
Other than that, the cons, I can think of off the top of my head, are;
1. that you'll have a single point of failure for the maintenance tasks of all servers
2. depending on the configuration, it may take longer to run the job (ie if it is synchronous / goes through the steps in order) - you can have all jobs running simultaneously on each server with independent jobs being unaffected by each other.
It's really down to preference to be honest and whether the central solution suits you.
Weigh up the risk of missing some backups against the advantages of being able to make uniform changes to the plan more easily.