Actually Custom Field Template Plugin is one of most useful WP plugins. Its functions go beyond usual "add-on" concept to solve a really important problem in WordPress: CFT give an interface to WP Custom Field engine. No. CFT allows us construct, adapt and layout our own Custom Field interface!.
Maybe WordPress custom fields (core) is the most powerful engine available to web developers to make highlevel sites, because throught them (custom fields) we can customize all things existing in the system. We can retrieve any data in any place, and create complex relationships to make anything in an easy way.
Those are the reasons I vote for CFT to be integrated in the WP core, (at least a lite version of it).
In the present, CFT is a free-bug addon. The developer, Hiroaki, maintains permanent activity about plugin evolution, and permanent interactivity with WP community requets. I don't see problem to WordPress Core Team think about this proposal.