The core Django developers will (and have) freely admit that the admin interface implementation is a bit of a mess. There is an enormous amount of technical debt in it. It is however not a "core" part of Django and there are many alternatives. I think most people would agree that the correct long term solution to the admin interface is a complete rewrite, however the cost of doing so is too high.

The html forms (used in the admin and everywhere else) have until now been generated from strings, however the next realise 1.11 (went to alpha yesterday) this has been changed to using the template tools.