I agree that forcing satellites into a stack is lame, unrealistic, silly, and greatly decreases their ability to protect a position. It would be much nicer to be able to surround a planet or warp point with them.
I disagree that satellites are worthless. A stack of them with long-range weapons and defenses can be pretty tough, and can be a useful addition to a defense, especially because they cost zero maintenance and they take up no cargo space when deployed, and they don't require supplies. Of course, two of those advantages don't make sense.
Fighters are also not useless in the late game, although it's true they can be smashed by PDC as well as main weapons, not to mention the ridiculous and wrong ability of ships to ram entire swarms of them to death.
Nonetheless, if you deploy a bunch of them with shields and late-game weapons, they can be a reasonable auxiliary weapon when combined with other weapons. They have the advantages of stupid unit stacking mechanics, no maintenance cost, and stacking damage per group. Large fighter swarms with shields can draw a lot of enemy fire, and can wipe out even large enemy ships if they get within range. This makes them useful in warp point defenses, for example, as well as in combined-forces attacks (with drones and seekers, for instance). If you've reached your empire's maintenance threshold, it will only make you stronger to have some fighters. They can also be used to test for minefields, other light duty, and to keep your enemies placing PDC on their ships. They're rarely decisive in the late-game, and are often slaughtered to no effect, but they are zero-maintenance and do have a few uses.
BTW, I won a major fleet battle in a PBW game against a superior empire, which would have been lost if not for my heavy deployment of satellites and fighters in the battle.
PvK