Right, so I've scienced the question "What exactly is the purpose and future of on foot game play in ED?". As a TL;DR I am glad to confirm my initial judgement of "fun". For more detail, it's once again story time with uncle Helmut. Feel free to skip the rest of my post if you can't stand it.
So, despite the anti-open-only stance I represent here and the impression of being anti-social and anti-multiplayer I might give, I am actually a member of a squadron (shocking, I know). Since its inception around the beginning of the Thargoid war, that squadron never had a real purpose; it might have been like something something humanitarian help the war effort something, but in reality it was just a gimmick for a loose band of looneys (that expression might have been the inofficial squad mantra for a while).
Now, in preparation for the Vanguards update, the squad leader has aligned the squad to a minor faction and colonized a system to be a home system for the squad. Naturally the dominating faction is of course the one he bought the colonisation rights from, but the squad faction was brought in as the fourth faction. So obviously it's time to run influence mission for that faction.
So I decided to do that. I didn't think of going on foot at first, but all the ship missions were just meh or unavailable due to me being neutral with the faction. Also, I cannot remember when I actually did on-foot missions - might be a year or longer.
So I disembarked and took a handful on-foot missions for the faction. All a bit on the sketchy side, and I might have gained a few bounties and points of notoriety in the process.
And I had some real good fun.
I have all the suits and weapons I ever want or need, so I didn't go to the settlements to grind them for materials, I went there with a mission. Or a few - some massacre missions, one steal power mission, a few assassinations, the usual. And it was a lot of fun. I always prefer the stealthy way picking off my targets from the rooftops with the plasma sniper, so the missions might have taken longer than run-and-gunning them, but I really enjoyed my time.
I also didn't really feel that often mentioned "disconnect" between on-foot and in-ship gameplay; maybe because it is most evident by the strict seperation of the rewards - ship mateials for ship missions, on-foot materials for on-foot missions. I didn't care for rewards, so it wasn't in my face. I enjoyed the process of getting the missions, climbing into my ship, traveling to the mission location, parking, getting out, doing my thing, getting in, taking off, flying to the next target, rinse and repeat. For my play session, it felt quite.... seamless? And I say that with that hard cut between VR ship gameplay and virtual screen on foot (I've made my peace with that).
In short: I had a great time and some good fun, and I think the game would be worse off if it didn't have that. There, I said it. Is it premium FPS content? No. But maybe it doesn't have to be to add value to your play session.
That's it, my bottom line: on-foot content is fun. Thanks for attending my sermon / coming to my TED talk / indulging an old man rambling.