So you've made a Fuel Air Explosive, also known as a Fuel Air Bomb, commonly referred to as an FAE.
Congratulations! You're a monster.
FAEs are nasty. As the provider of the biggest booms this side of a nuke, the FAE can level the playing field and the grid square with massive explosions that are just close enough to the near side of WMD that they're not outright banned by convention.
Without getting too technical, on the grounds that I'm on enough watch lists already for my own subs, FAEs are basically giant, bomb shaped fuel tanks with a dispersal and ignition system. Once they reach a preprogrammed point, they pop the casing, disperse the fuel which atomizes into the atmosphere, and then lights it. The resultant blast strongly resembles that of a nuclear airburst. There's a mushroom cloud that throws out enough heat to set fires at over a kilometer, a shockwave that can level buildings and toss tanks like toys, so on and so forth. The only thing you don't get is fallout, which is why they're not verboten in modern warfare, and they're not quite as large as a nuclear blast.
It should be noted that the proper FAE should not be confused with thermobaric weapons. Although similar, thermobaric weapons are typically designed to work inside enclosed spaces such as bunkers or caverns, rather than in airbursts. Thermobaric weapons are smaller, and often take the form of bunker busters. FAEs are necessarily huge, to the point that the largest have to be airdropped out of modified cargo craft because they just don't fit on bombers.
But hey, if you've got the airlift capacity, why not blow your enemies off the face of the planet?
Well, for all their raw destructive power, FAEs have some startling weaknesses.
For starters, they're massive. Really, truly massive. They have to be. Carrying enough fuel for a meaningful explosion is no joke, and if you don't build the things to scale, there's no point. Conventional explosives, although less powerful, are still perfectly capable of getting the job done unless you've the need to level the playing field and any structures within a few hundred kilometers.
They're also slow. Like, hooked to a parachute slow. They have to be. They fuel has to disperse in a fairly controlled manner, otherwise the device is useless. They might have a huge amount of momentum exiting the aircraft, but they have to check up before they detonate, or it's all for naught.
On top of all that, they're not the most heavily armored things in existence. Unlike a normal bomb, which initially tries to contain the force of the explosion in its casing in order to create more pressure, the initial bursting of an FAE is only enough to spread the fuel over a calculated volume of atmosphere. The actual explosion comes later, once it's atomized enough to be effective. And considering the already impressive weight, there's not much point in tacking on extra when the aircraft is going to be struggling enough as is.
So these things are big, they're slow, and they're lightly armored.
In other words, they're an air defense crew's dream.
The reason why these things were used to such aplomb in the real world was the simple fact that the technology to shoot them down simply wasn't around at the time. Or if it was, the targets didn't know enough to shoot at them.
Meanwhile, in Star Wars land, we have air defense artillery capable of blasting starships from the sky at distances that straddle the line between awesome and ridiculous. We have sensors sensitive enough to pick up a flea farting on a tick's ass. Our sensors are so sensitive, it's a wonder they don't start listening to Linkin Park while writing terrible poetry about how their parents just don't get them.
Big, fat, and slow plus emo AA cannon equals ineffective weapons system.
Because the final weakness of the FAE is the fact that things have to happen in a fairly controlled manner if it's going to work at all. Light it too soon, and you've got a big tank of napalm that'll likely burn itself out before it hits the ground. Light it too late and the cloud isn't dense enough to get the proper reaction. Pumping a couple of blaster bolts into it is gonna render the thing useless, and the chances of only a couple hitting it are slim.
That's not to say these things don't have a use. If you're clearing out forest for an LZ, they're magic. That was the original purpose of the Daisy Cutter anyway. If you want to take out an armored column of primitive troops whose AAA systems prefer Metallica to 30 Seconds to Mars, they'll work wonders.
If, on the other hand, you're attacking a modern force with modern AA guns who just so happen to be expecting an attack from the air, maybe you should go a different route.