I don't understand why a square grid is still the default for tactical combat with its clunky diagonal distance measurements. I admit that it aligns better for environments with lots of straight lines, but for anything outside of that it's just as messy as a hex grid.
The only other thing I can think of that would be different is that some of the radii would change the amount of spaces effected by certain spells. A 5 foot radius is 4 squares, but only 3 hexes.
If I want to switch between the two I have to flip my vinyl table mat. That means moving all the minis, books, dice, drinks, and paper off the table.
Why would they do this?
As much as I love hexes, the Starfinder will see even more locations full of straight lines - starship and starbases corridors, and advanced settlement streets.
Hexagons are futuristic.
Hexagons are futuristic.
No, we must do everything in heptagos! Embrace the future!
Take a look at the architecture of your home, work, and most other buildings you go into. Predominately, you will see straight lines and right angles. Sometimes curves are added for visual flair. What you will generally NOT see is room configurations that are hex-friendly. Walking down a hallway or being in a room with a hex map is far more awkward than with square maps, as parts of a lot of hexes will be cut off whereas squares map to it a lot more cleanly.
So, the "environments with a lot of straight lines" would be "the vast majority of environments your players will be on when doing tactical combat." Buildings, starships, space stations all largely have straight corridors and boxy rooms (Shirren ships being an exception here). Otherwise the players are out in the open in which case squares and hexes are equivalent in how "awkward" they are.
There are many ways that hexes mess up. There is diagonals, there is even going straight north/south (or east/west depending on map orientation), there is scaleability for areas and such, difficulty of measuring larger areas in hexes, and more. Hexes are most useful with facing, but carry a significant cost.
I use squares because the Paizo and Heroic maps that I like all are printed with squares but I used hex maps for years without any problems. I still have some nice printed hex maps that I will pull out from time to time.