I'm rather surprised that it seems that as of a few years ago there was still no easy way to accomplish this.
I don't think we're going to see this capability in this current incarnation of Elite - it simply hasn't been designed with this in mind. I believe it has to do with the database maintained of explored systems.
The ED galaxy is mostly procedurally-generated - it's the only way to create a full-scale replica of an entire galaxy with 400 billion stars in it (and if each star system has an average of 10 planets, that's 4 trillion planets), and not need a real-world planet-sized supercomputer to keep track of all the data for it. But there is a tiny subset of the galaxy that has actually been explored and visited by players, and it is this set that there needs to be a "database" for.
This database is large - of those 4 trillion planets, probably about a billion have now been mapped and tagged in some form - so it's got to be simple. To store First Discovery data for a planet, you need to save three numbers: the unique star system number, the planet number within that star system, and the unique commander ID number of the discoverer. The question then arises, for a giant database, which of those three fields do you use as your primary sort option?
The game needs to know the discoverers of specific star systems quickly, because it needs to look this up whenever a player enters a star system, or loads up the system map for a system they've already visited. The game doesn't actually need to quickly know a specific commander's list of first-discovered planets. Therefore, the database is sorted by star system number.
This in turn means that in order to request a specific individual commander's list of discoveries, you'd need to search through the entire database, looking at every single planet and star in the database, seeking the ID number of that specific commander. For a database with a billion or so entries, that could take a while. Oh, and it has to do this three times, because there's three databases now: Discovered, Mapped, and Footfalled.
Personally, I wouldn't mind the option of spending five minutes or more, pausing the game while it searches the entire galaxy's databases and generates such a list - especially if it then saved that list locally for perusal at leisure, until I requested an updated list. If resources are the problem, I'd even pay real-world cash to be given that option. But apparently, FD believe nobody would want to wait that long for their own personal discovery list to be generated.
