I like how you state that as fact and expect everyone to believe you.
And which Mon-Cal vs. star destroyer battle are you comparing to? The one where they specifically engage at point blank range?
I'm sorry that I can't give you specific episode names and time stamps, since I have no at-hand access to Trek material (nor would I remember specific episodic instances even if I did), but having seen more Trek than is probably healthy for me, all I can say is that I've seen ships at warp fight each other on numerous occasions across two or three different series. I don't proclaim to be a Trek expert by any stretch of the imagination, so I'd hope there's someone much better informed than I to clarify things. And the engagements I was talking about were during the Battle of Endor, since that's the only time in the films I can think of where we see those two sorts of ships engage. If you want a different example, the Star Destroyer at the beginning of ANH was right on the tail of the Tantive IV while trying to capture it, and if you're expanding this to the prequels, the two destroyers at the beginning of ROTS were broadsiding from point-blank range as well. Like I said, I don't have any specific evidence to back things up on the Trek side of things, but I've always been under the impression that even at impulse speed, Trek ships seemed to have an extraordinarily fast closing speed, on the order of thousands of kilometers a second, and that combat from those ranges was not uncommon.
They weren't worried about the asteroids at all, in fact the novelization describes multi-megaton impacts hitting them for days on end. Only one Star Destroyer was damaged in the asteroid field, and that's because its shields were down for a holonet conference and it was already damaged from the ion cannon at Hoth.
I've already said that I'm considering neither the novelization nor the figures that it contains, since it's really so much fluff in the end. If you want to get down to brass tacks, the asteroids we saw in ESB were rather dinky as a whole (unless you count that space worm hangout), and they didn't seem to be moving at much of a relative speed to the Star Destroyers at all. Hardly "multi-megaton" material, considering how big and how fast a meteorite has to be to cause that level of impact on our own planet.
Furthermore, Star Trek battles almost always occur at only a few ship-lengths away with slow maneuvering. Star Wars ships can hit enemies from light-seconds away in some circumstances. Warp Strafing is a Trekkie fanfiction invention that has never been seen in canon.
Without concrete evidence, I can't do anything more than claim that you're way off-base here from my own viewing experience, so I'm not going to attempt to do so. What I do know is that I don't ever recall seeing Trek ships engage at only a "few ship-lengths," nor did I ever see Wars ships engage at "light-second" range (again, the Death Star might be an exception, but it's kind of a gamebreaker by its very nature anyway). The term "warp strafing" came up in some random argument I found via a Google search, but I can't confirm or deny the episodes it referenced; what I do know is that combat between two ships both at a similar warp speed seems to be fairly common.
If you want to talk about what we see onscreen, look at the asteroid scene in episode II when Slave 1 (a modified civilian patrol ship) demonstrates easily gigaton - level firepower.
It also demonstrated the most scientifically-inaccurate weaponry I've ever seen in sci-fi. "Hey, let's kill things in space...with sound! Brilliant!"
Okay, look...this whole argument got started around a one-off comment I included in my first post in here that wasn't even the main point of what I was trying to say. I will freely admit that I'm not capable of giving this argument any informed justice, since I simply don't have references at hand to pull up and use as examples. (Now, if someone wants to permanently loan me a thousand bucks' worth of DVD sets, that can change...) I don't want to waste anyone's time pulling a he-said-she-said style of discussion, since the topic's deserving of something far better-informed than that. And besides all of that...I really, really
loathe space-battle-style arguments, and the last thing I ever wanted was to become embroiled in one.
I'm going to do everyone a favor and pull out of this, with the hope that someone who actually does know what they're talking about can continue it somewhere/when else.