During several livestreams since the Alpha launched, the Devs have pointed out that the new iteration of the Stellar Forge planetary generation technology will not be implemented during the Alpha. The alpha's purpose is testing the core mechanics (obviously), not showing off the new planetary tech; that will have to wait for the full release. The graphical overhaul has been implemented, but not all of the new procedural generation tech,
So while we get beautiful views already and while we get to land on new classes of planets in the Alpha and explore canyons and such on foot, we will have to wait until the full release to see beautiful worlds like the ice planet from the combat gameplay preview.
I thought this would be a helpful post as I've seen a lot of people (both here and on the forums) who aren't aware of this and thought the worlds they were landing on were somehow representative of the final product, which it caught me by surprise. Hope this is a helpful clarification!
Here's a source from the forums, courtesy of u/Neqideen:
"Planetary Tech, including geometry, will not be final until release. However, players may see coloration changes throughout the Alpha phases."
Edited for clarity