Where I work client auth is used for a good (and growing) number of internal services. Client auth is simple to use - our internal services are given the usern

Where I work client auth is used for a good (and growing) number of internal services. Client auth is simple to use - our internal services are given the username from the CN, which they use to perform authorization checks. For a lot of simple internal services that don't require two-factor auth it works great. Am I missing something better? (We already have the infrastructure in place to deal with client keys)