Trope A Day-Orbital Bombardment

Orbital Bombardment-Regardless of if it’s with k-rods (kinetic energy weapons) or directed energy weapons, orbital bombardment is a threat to any planet that doesn’t have city shields.  Since a shield that can protect a city isn’t something that can be moved easily, the rest of the planet is vulnerable.  However, area bombardments are not used by any of the major races until the Horizon War.  There is a moral component (there hasn’t been a war that has involved reducing a planet to glass before then), a logistical component (if Changelings killed off their food source, they’d starve), and a political component (for the most part, the usual result of somebody taking over the high orbitals was a quick surrender, followed by political negotiations).

During and after the Horizon War, mass bombardment of planets became a valid strategy, especially with Changeling-held worlds.  The capability of such bombardments made grav-armor more important, as such vehicles were hard to target with orbital bombardments short of a saturation strike.

Trope A Day-Pony Shield

Pony Shield-Doesn’t work very well when death is cheap, you have cortical backups, and you can be back on your hooves in a few days after they pull your cortical stack.  This means that taking hostages isn’t a valid option.  Of course, threatening to smash the cortical stacks works as a valid threat, but not as a valid shield against attacks.

Also, actually carrying through with killing hostages, even if they’re re-sleeved, is a premeditated murder charge in just about every nation.  Done often by Changeling queens and empresses, whom use their captured food sources as a defense against hostile fleets just nuking them from orbit.  All this means is that they have to send in the ground troops to get the hostages out.  Then nuke them from orbit.