Energy weapons, namely lasers, beams, and electromagnetic wave weaponry (such as a Microwave gun or a X-ray gun) seek to destroy material by raising its internal temperature or otherwise alter the molecular bonds so that the material's molecules will unravel themselves.
EMW weaponry (including lasers) all travel at the speed of light, so their precision is phenomenal and is not affected by gravitational forces for sub-AU distances (like all types of kinetic energy weapons are).
Beam weaponry (including lightning-type weaponry) for the most part behave exactly the same as kinetic energy weaponry, but have the capability of being a continuous stream. Additionally, beam weaponry can have the same effect as laser and X-ray weaponry on the temperature and molecular stability of material.
Note that energy weapons may also be area effect weaponry, such as traditional bombs. However, these types of energy weapons have far higher energy demands (equivalent to the cubed amount of energy needed for directional weaponry, I think) as well have curious methods of detonation (self-destabilizing plasma grenade, anyone?)
A weapon that can accomplish most if not all tasks from one fuel/source (imagining gas being used for plasma weapons that accomplishes everything from nuking cities to a hand held blaster) is what is desired.
Ironically, that's pretty much how gunpowder works. Granted there's a whole slew of differences in the chemical compisitions of the different types of gunpowder, you could have an entire arsenal that uses gunpowder as its primary propellant. However, the main disadvantage to using only one fuel source for al[l/i] your weaponry is that you make the propellant/energy source production plants a fat target. Diversification guarantees that, even if one source of propellant/energy is denied, you still have a large number of other weaponry that doesn't use it.
As an aside, Beam and EM (rail- and coilgun) weaponry could be the next shotgun, whereas a number of different types of ammunition will give unique effects and tactical advantages/disadvantages. (EMW weaponry can't do that)
And no, i don't have many ideas of what energy weapons could still be used for other than just point and shoot and still be a weapon (i've got like two ideas, but both would require some serious advancement in energy weapons to work). It's hard to think of; point and shoot is pretty effective in standard warfare.
Point-and-shoot almost guarantees that the stuff your firing doesn't hit any friendlies or otherwise would-be neutrals. Area-of-effect weaponry destroy's anything within its killzone, so surgical strikes with AoE weaponry is impossible and has a high probability of collateral.
I disagree with the gunpowder point to an extent. Energy weapons have the potential to simplify weaponry. What brings to mind is balls of plasma being hurled at a target. Hell, if you can nuke a city with a big ball of plasma, and then channel that down to something less destructive like intercepting missiles or smaller targets. That's pretty multi-use. In todays world we use different materials for different kinds of uses for weapons (we don't rely on only one thing to get the job done because we can't currently at least). However, also in the real world, energy weapons will definitely be just as diverse.
Reminds me of star wars where the primary weapons are lasers powered by gas easily harvested from around everywhere. And they do just about everything with lasers, the fuel, and energy required for these energy weapons in star wars. Everything from personal blasters to destroying planets. One energy source and fuel for a weapon can be better than the other in versatility (then again, i brought up star wars, that's funny enough, even still, something like this is a long way off; it may not be the best way to go either(my opinion of star wars weapons is as follows...bigger laser, bigger laser, bigger laser bigger laser, it's really tiring with almost zilch weapon diversity in a sci-fi fantasy universe)).
If you can nuke a city with a big enough plasma ball, and make a plasma blaster, and make plasma turrets for taking out ships. That's pretty cool then. Of course certain uses will require more fuel and energy than others, but you could be dealing with less different materials to get the job done. If you could do all of that with plasma (theoretically), then you wouldn't need plutonium for nuking, bullets for other uses, and standard explosive bombs and missiles for others. Anyway, some fuels are more multi-use than others. If plasma could be used for all of that cool stuff, that'd be nice. For now there's different propellant fuels for different uses. Gun powder for bullets, and a myriad of different fuels for jets and rockets.
As far as what energy weapons could be used for other than point and shoot; that's a toughie. I'm sure the human who invented the bow and arrow had a great brain **** for all of the other humans who didn't think of other ways of attacking. Sure you can make point and shoot a lot more efficient and effective. But, what about non point and shoot applications for weapons? An area attack is a great idea indeed.
As far as anything goes. I'd rather stick with non energy weapons. It's tried, true, works, and will keep working. I would only go to energy weapons if it simplified everything. However, that doesn't mean that moves to simplify non energy weapons can't be done (not insisting people were saying it couldn't be). Research into kinetic energy weapons could easily reduce or eliminate air dropped bombs. In that scenario, i see more of an equivalency in energy expenditure to using a railgun from a distance compared to transporting the weapons, the bombs, the bomber jet, and fuel for the bomber, and the bomber getting to it's target to do it's job. One just saves you from needing to send in a human directly over the other as far as i'm concerned for the advantage.
But, yeah, i myself would rather stick with non energy weapons. Beam cannons and plasma weaponry does sound really handy though, for space battles; too bad atmosphere gets in the way of range for lasers and plasma. Aside from being handy in space, in the area of point and shoot these energy weapons do supply damage in a different way that is more or less desired.
