any reason to keep a DD 2.0 audio track

This is a bit off topic from Kodi but I figure a lot of people here may have an option.
In the absence of surround sound is there any advantage to using AC3 (or DTS for that matter)? I’ve got some older TV shows & movies that I want to archive and I’m wondering if there’s any reason to not reencode the audio to AAC. Some of this content is not just in stereo but in mono.
Any thoughts would be appreciated.