Inside-to-inside NAT aka NAT loopback solves hairpin NAT issues when accessing a web server on the external interface of an ASA or similar device from computers on the internal interface. This prevents DNS admins from having to maintain a duplicate internal DNS zone that has the corresponding RFC1918 addresses for their servers that are NATted to public addresses. I'm not a network engineer, so I might be missing something, but this seems like a no-brainer to configure and implement. Asymmetric routing can be an issue but is easily mitigated.
In my experience, network admins/engineers prefer that systems folks just run split-dns rather than configuring their firewalls to properly handle NAT hairpins. Why is this?