I've logged about 600 hours, which isn't a lot compared to most people, but it's easily enough time to master the basics of any game. And I've struggled with certain basic things for YEARS.
It took me until literally five minutes ago to realize why: my TV is too small. Your HUD gives you all kinds of helpful information, but it's quite small, and if you're too far away from your TV, you'll likely never notice it. I just noticed today, after dozens of planetary landings, that the HUD gives you alignment cues when close to the surface. It gives you a speed indicator and an altimeter with glide mode height shown right on it. I've never seen that before, BECAUSE IT'S TOO SMALL.
Now that I know that, I can make it a point to walk over to the TV when it's safe to make sure I'm seeing all the information it's giving me. Once I know what it's telling me, I can interpret it from the couch.
Hopefully this helps someone else with the same problem.