The fact that units can't see 5 meters in front of them is ridiculous. If there's 2 t1 land armies moving towards each other I'm pretty sure it's actually impossible to turn back in time once you see the opponent units even if you were to pay 100% attention. Not to mention certain (direct fire) units not even being able to use their weapons at max range, because they have old eyes or something. And let's not even get started on air...
Idk people probably take t1 scout spam and t1 radar creep for granted at this point, but it doesn't have to be this way. T1 scout spam in particular doesn't add any extra dimension to the game.
Yea, increasing vision+radar radius would make the game "easier" in some ways, but at the same time it would allow you to make more conscious decisions (=more skill) in some cases where you've lost your radar, rather than just retreating with tail between your legs. Imagine flying over your opponents base and actually being able to see the AA that is shooting at you for instance.
Btw, while the title says "all units", there's probably some exceptions and different units probably deserve slightly different treatment in general. The point I'm making is just the general design direction of increasing vision/radar ranges in the game.