There's a lot of cool localization stuff in the works, but as mentioned by Graf here, old-style binary font lumps (i.e. FON1/FON2) don't mix well with the new system.
Though FON2 ought to have been long-obsoleted by FONTDEFS, There's still one thing that FON2 can do that FONTDEFS can't: set GlobalKerning. This is often used to merge the 1-pixel border between letters for Doom-style font graphics (i.e. set it to -1) to do things like make DBIGFONT look like how the text is formatted on Doom's CWILV graphics. A "KERNING" specifier for FONTDEFS would close that feature-gap and let all of us kick FON2 to the curb for good.
Because someone's inevitably going to suggest full per-character kerning: please reserve that topic for another thread. This is just about exposing support for the feature that already exists, which is independently useful as a "border collapse" feature.