Pretty much this imo.
I'm all for space legs but since most of the stuff you can do in ED is attainable with a few clicks, then where's the need to get out of your ship or SRV? For this reason, space legs will the be the last thing on FD's mind (if at all).
If space legs is to be a thing, then it would have to open up more options like horizons does.
Meeting faction reps could give more mission options such as different rewards, negotiation over higher rewards and so forth.
As to missions, well there is only so much you can do in your SRV and ship. So using space legs as a continuation of those missions to make them a bit more interesting.
Which could include boarding abandoned wrecked ships. Use those new scanning features with the mega ships to pinpoint areas where you can board the ship. Use a limpet to hack the terminal to open the airlock, EVA to the other ship and explore the inside to get to your mission objective, over come natural and possibly not natural obstacles on the way. This is just one example.
You would obviously be paid more for doing more, but that stands to reason. No different to real life.