A few miscellaneous points for issues raised throughout the thread
1) In comparing weapons it's not just how big the boom is at the end point because directed energy weapons function differently. You want to figure out the equivalent of the overpressure wave, heat, and radiation to get an approximation of equivalent energy. I'll explain more below
2) "Energy bleed" doesn't help solve anything. Dumping the energy into the air around it doesn't make it not damaging, i means you end up with a very large line source for the heat and radiation (that heavily ionized air will be shedding particulate and energy radiation). This is less consistent with the visuals than we see
3) Blast size at the end point should be nothing close to the appearance the blast of an energetic equivalent bomb. Mike explained this about a decade ago
HERE, but basically an explosion is the function of the mols of gaseous material and their overpressure (a function of detonation velocity or how rapidly the material is made gaseous). With TNT or RDX, the light elements provide their own energy and gas as they drop to a lower state (translation: "go boom"). With a direct energy weapon however, they need to apply a great deal of energy making the target a gas and then exciting it to that level. Particularly when you are shooting a planet and you are hitting mainly silicon dioxide or iron.
I built a spreadsheet that calculated this a while back - it isn't optimal because I assume perfectly spherical geometries when really it should be more hemispherical/crater. But the gist is that it takes several orders of magnitude more energy to get the equivalent of a bomb. For example against a SiO2 target, to get the equivalent of a 1 kiloton detonation it takes 6 *10^19 joules released in 0.000756 seconds. That's faster than what it looks like a TL applies, so the math needs some more work, but basically it takes a 14 gigaton TL to approximate a 1 kiloton bomb. This isn't a linear relationship btw, a 100 ton bomb equivalent ("tbe" from here on out) is 6*10^17, 10 tbe is 10^15, when you get down to like 10 kg of tnt you are talking 10^9 tbe. So it isn't that far off from what we see. I should refine this more but I have a lot going on so I probably won't.
4) Big explosions are highly inefficient. The useful part of an explosion is the overpressure wave and fireball. Those scale with the cube root of the energy. If you want to wreck a country, 1000 kiloton explosions are more effective than 1 megaton explosion. You simply get more coverage and saturation for it
so now that we've covered that it takes orders of magnitude more energy to get big booms, and that big booms are less militarily useful, let's go to the final point
5) Cranking the reactor on max to fuel big booms is suicide. A starship running full power is terrible and no sensible commander wants to do it for anything but emergency manurers (eg closing the trap at Endor). The fact is that the higher your power:mass ratio is the better you can shoot and manuver, but also the faster you run out of fuel. And at peak power the operating time for star wars capital ships is low single digit hours. Physics still follow - we know the ISD masses ~10^12 kg based of its acceleration and power, we know its reactor has a peak output of 10^25 watts, which means that if every last microgram of that ship is fuel ( and it isn't) then it can at best operate like that for 10,000 seconds. Or about 2 hours, 45 minutes. An old style BDZ was basically an hour, that means it has 1 hour 45 minutes at best before it is dead in space and vulnerable. That is assuming it was fully fueled above its target - it is had been operating and deploying prior to that as expected, or if it had to fly there, going full power for an extended period may not even be possible, or if it did it would leave the ship easy pickings for much smaller craft. Something like the Invisible Hand melting a planet's surface would be a shocking act because no commander would do that, Grievous would because he can redirect the fleet and its logistics train to allow it to be done and make a point, or an Imperial commander could do it against an under developed world and expect to limp back to station without encountering a hostile. But even the bloodlust of the most moustache twirling moff would be slowed by realizing he doesn't have the gas in the tank to melt the surface and get home, so use the medium TLs to perform the equivalent of conventional bombing instead
6) Missiles don't have a delta-v advantage. The old view from the libertarian scifi authors of the 70s and 80s was about how it was easier to drop something down the gravity well than throw it up. Which is true, <i>provided you don't care what you hit</i>. But if you want to hit a specific target to achieve an objective and not just skip rocks on the ocean, you have to have your missiles do a lot of manuvering - and it unsurprisingly works out to basically the same delta-v as it would take a launch from that spot to hit your ship.
7) No cover in space, and if you can see them, they can see you
So if small booms are better, bombs are more energy efficient than TLs by several orders of magnitude, emerging to hit hard leaves you running on fumes with no cover, and any missile or missile bus you send needs a massive flight envelope to ensure they hit the target
8 ) the optimal response is atmospheric insertion capable bombers. Give them an escort and a few proton torpedoes for defense, load them up with small precision guided conventional munitions to hit your objectives, and you can effectively control a planet via targeted bombing run from a carrier in orbit much easier than you can having an ISD show up and roll out the topside HTLs. When the ISD does show up, it wants to use low level MTLs and lesser guns both by fuel constraints and destruction effectiveness. If you are going to consistently be doing insanely huge attacks on a planet's surface you might as well build a speciality platform that is huge and almost all fuel - the Death Star
Which is consistent with what we see.
