Skip ahead to the prequel series and we see quite a bit more holographic technology. Again, some of it is very cool. The holographic Darth Sidious is again made to look more threatening by being a ghost-like kind of entity and yet quite 'present' among his minions. Likewise, we see a meeting of the Jedi Council where some of the members are attending 'remotely' via hologram. All of these uses seem practical enough in their own settings.
But there are some cases where the use of holograms just seems excessive, silly and/or impractical. Throughout the prequels, for instance, people seem to use holograms as the sole way of communicating. Why? Why do you need to see a full 3D representation of someone when all they're doing is calling you to tell you that they're going to investigate such and such. And then you have Palpatine, giving Order 66 to his clone troopers. Why a hologram? In fact, it looks downright...silly. With millions of tiny little Emperors giving out orders to the troops. I was struck by the same thing in Empire Strikes Back, when a tiny Darth Vader is demanding an update on the assault from General Veers. This kind of representation does little to maintain the frightening image of Vader or the Emperor. In fact, they're almost 'cute'. Awwww... look at little Vader! Isn't he cute when he's angry! Who's a cutie! You are! Yes you are!
In ESB and RotJ both we see that there is 2D visual communication available (in the scenes where Vader kills Admiral Ozzel and when Han pretends to be an AT-ST pilot and tricks the guys into opening the shield bunker). This would seem to require less effort, technologically speaking, and still suffice for most communication needs. In fact, with these visual comms it seems you could do a lot more things—like say...pan your 'camera' around and give the party on the other end a visual of what you're looking at. You apparently can't do that with holograms—as witnessed in the scene where Kenobi is attacked on geonosis and chased 'out of camera' by a destroyer droid. And when you throw in the fact that holograms are apparently in 'black and white' only (okay, blue and white) they just seem a lot more limited. For that matter, considering the apparent level of technology...why can't holos be 'in color'? The one in the death-star attack briefing in RotJ was?
In any case, I am rambling. Suffice it to say that I think the 'coolness' factor of holos has been overrated. I don't see why they'd be used ALL THE TIME for mundane communications as they seemingly were. I can see them being used in three dimensional briefings and in situations where you want to at least mimic a physical presence in an area, but otherwise they just appear frivolous.