There is the basis in place for Exploration as a primary playstyle to be much more rewarding and engaging if Frontier were to expand on what's already there. Here are some things that can be done to give this playstyle a much needed buff:
Why can't I land on all terrestrial planets? I get not landing on ELWs due to the complications in rendering and simulating such biomes, but why aren't all airless and thin-atmosphere terrestrial worlds landable? Why can't I land on atmospheric worlds greater than 0.1atm? If you can handwave away being able to survive on those planets with ridiculously hot and cold temperatures already, why does it matter that there's an arbitrary heat, cold, and atmosphere limit? If you must make it a grind, make engineering the Artemis suit necessary to open up more planets to land on with greater temperature and atmospheric tolerance.
What's with the small biodiversity in the galaxy? With 400 billion stars there should be new biological sources for Exobiologists to analyze and collect. Basically expand what is already there, it's a great start! Just build on it!!!
More stellar phenomena. Space is a big and dangerous place, but it doesn't feel like it. The worst thing you have to worry about is a misjudged neutron cone or witchspace dumping you in a binary star sandwich where you're the meat. Lagrange clouds are cool but super rare, the space crystals are cool too! I've yet to see a lightning cloud yet but those things really add a lot to the exploration experience and again, expand on what's already there!
Probably a huge stretch but the Thargoid and Guardian stuff is kinda played out, it would be a great time to add some Exploration based ruins of non-Guardian, non-Thargoid races. It doesn't have to be anything big but think about it, you're scanning a planet and get a signal source on the planet. You drop down and it's a ruined building with some data points that have fragments of a log or poem or something, and there hasn't have to be anything more than that. No grand civilization, no new grind, just a ruined building millions of years old and that's all that remains, so you move on. It would make exploration feel immensely satisfying, like you're doing something worthwhile and useful with your time and give you more reasons to land on planets.
Community Goals focusing on exploration! Rewards for who can find, plot, and navigate the shortest routes between places, or dedicating CGs for scouting and mapping Sector X/Y/Z as part of an upcoming expansion CG or for mapping new areas for colonization in-story. Give us a reason to get out there beyond our own ambition! It would also encourage others to get involved. Like the Distant Worlds expeditions, those had sanctioning from FDev and became milestones of player engagement.
Can we get a way to integrate a captain's log that auto-imports to Inara and EDSM's logbooks? That one's more just for me though but since I'm writing all this I might as well ask.
Anyway those are just some ideas I had for improving Exploration, making it feel better to players, provide a more meaningful play experience for them, and would be fairly resource cheap to pull off, compared to something like adding major systems like Engineering. This is mostly just building on what FDev already has in place, because their biggest problem as a dev studio is that they lay the groundwork for a great mechanic and then fail to really develop them further. If you're lucky you'll get a systems sweep over it and an overhaul like Engineers and stuff, but for the most part the features feel anemic and wanted to throw out some feedback that could help with that.