And even that is small potatoes compared to the deeper problem with those databases: record size. A lot of the tables in those systems are close to (or at) their maximum record size. Inserting another 2 characters is simply not possible.
And even if you could simply insert another two characters, there is an unknown amount of code that parses the records starting at the nth character... all of that code would have to be examined and tested.
Resizing database columns would be a painful couple of days. Full regression testing of some of these systems? Weeks and weeks.