It has been requested many times before, but it is not a simple thing to add, and its benefits are dubious. Even after many years, there are still few applications that support OpenType features, and even in those that do, not all users are aware of how to make use of them.
This Issue for OpenType support in OpenOffice was started in 2003, and has 175 votes, but still no target milestone.
Adding OpenType Features is not too difficult if you’re determined. Once you have written the script, it is a relatively quick process to add the same features to other fonts. I have added several features to most of my fonts.
The bottom line is that this feature would take a lot of programming effort, that is hard to justify for the small percentage of FontCreator users who would really like to have it.