I think the question about missiles, especially advanced ones is quite good. And there have been some excellent replies on the subject as well.
To rehash some points:
1) Lower tech races still tend to use missiles in some capacity for ship to ship combat. The Drazi, Centauri (don't forget the mine looking missiles their ships under Drakh control fired at the drazi in S5), Narn (energy mines, which seem to be a large missile of some kind) and Earth all fall into this category. The only races that don't seem to use them for ship to ship combat are the Minbari, Vorlon and Shadows. Their beam weapons are far more destructive than anyone elses and they have the power sources to back them up. So it makes sense they prefer to use those on ships.
2) Speed/guidance: Missiles are slower than energy weapons of any kind and they require a lock on and guidance to their target. One of the biggest problems with Minbari ships that Earth had was how good Minbari EW was. They simply couldn't get a target for any weapons. You can't hit what you can't shoot. Plus Minbari defensive tech is much better than Earth's so its to be expected their point defense is better too (better sensors, computers, targeting arrays and so forth).
3)Warhead - Ships could probably carry missiles large enough to do serious damage and a fusion bomb is nothing to sneeze at. Fighter missiles probably are not as destructive and probably used against ground targets, other fighters and less well defended targets than warships.
So do missiles have their place? Obviously they do because so many races still use them. Are they a superior weapon? Not really.
Now for some practical comments. Energy displays are easier to render than missiles and look neater on the screen.
Also serious missile engagements would require a lot of missiles, long flight times and so forth and I have a feeling that would look rather dull on TV.
Energy weapons are actually slowed down. Energy travels at or close to the speed of light so really by the time you "see" a beam its already hit you or about to hit you. A "defense grid" is really useless against energy weapons because even the fastest computers can't target an energy packet moving at light speed. I'm not even sure one energy beam hitting another would stop it. Based on that I'm guessing what the defense grids are intercepting are some sort of missile rather than true energy beams. I'm pretty sure we see the Defense grid actually intercepting incoming fire only against Centauri and other lower tech aliens and fighter craft. You don't see them intercepting against slicer beams or anything else.
Now it is possible that the bolts from a pulse cannon and similar weapons travel at less than light speed, which would make interception possible but incredibly difficult. Assuming that your EW is good enough to burn through your enemy's you might be able to calculate trajectory and firing paths based on the way their weapons are pointing and then fill space with a volume of fire and pray for a hit. In this case a defense grid may work against some types of energy weapons.
As for photon torpedoes and the like, I'm not sure how feasible they really are technology wise. The Star Trek encyclopedia mentions that photon torpedoes travel at warp speed which I can't buy. They travel way too slowly for that. They also underestimate the destructive power of anti-matter. Judging from how many hits various ships can take from these things, their warheads would have to yield very little. A fusion bomb that hit the Enterprise would blow it to pieces, but a photon torpedo just puts a hole in the hull.
One thing I like about B5 is that for Earth and other races at about the same tech level and development their technology is still reasonable. No super fancy shields or anything like that. Its only when you reach the Minbari, Drakh and other races that have had space flight for a couple thousand of years do you start moving into more unknown territory.
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Lyta lives!
