Welcome, Shadowrun Man. I hope you stick around for more than just "dissing" d20 Modern! We have excellent Dungeons and Dragons Forums, and hoepfully you might find something else you like.
That said, this forum is for discussing d20 Modern. You are entitled to your opinion, and I'm glad you have given it, without insult or putdowns.
Now, my response:
Shadowrun vs. d20 Modern isn't to me a question of superior systems - it's a question of superior mechanics, and modelling the kind of action you wish to model.
First, for me personally, Shadowrun is a fun system, but FAR too messy to play. I have always been turned off by "dice pool" systems, especially the more dice they have me roll and count successes. The usual result is that combats involving more than 4 or 5 combatants on a side are too difficult to run, taking several hours to finish, whereas a d20 System combat can be finished quickly, and the plot can continue. It gives fans of combat action what they want, and gives fans of the story more of what they want.
Second, firearms are not that easy, as anyone who has ever been in a firefight will tell you. (I haven't, but I am friends with about four ex-military and ex-law enforcement who have.) On a target range, there are no distractions, no bullets whizzing toward you, and being calm (though not exposed) in a firefight is one of the NUMBER ONE things that a good combatant can learn to stay alive. Almost any weapon, not just firearms, are a matter of "point and shoot;" however, being in a combat makes this difficult.
Third, according to shadowrun rules, it is a DARNED HARD THING to hit someone in a firefight, not an easy thing as your post suggests. The target number is a "4" on a d6, and goes up for things like cover, darkness, target in motion, etc. and goes down for people with smartlinks, laser sights, other cyber-modifications, etc. So unless you are a street samurai, the only thing that will help you make that shot is your combat dice pool, which gets spent pretty quickly in a fight with mroe than one round. Six of one, half dozen of another.
Fourth, d20 Modern is meant to model action movies, not the Six O'clock news. From page 5 of the rulebook:
Combine the elements of the modern world with the imagination-powered engine of the d20 System... and you can leave behind mundane reality and embrace action and adventure of modern fantasy.
Modern Fantasy?...any story set in the modern world the feature heroic characters in dramatic situations accomplishing larger than life feats falls under the category of fantasy.
...It's the fantasy of action-adventure movies -- slow-motion gunfights, bone-rattling explosions, jaw-dropping martial arts battles, heart-stopping car chases, more explosions, and over-the-top plots hatched by the most terrible villains.
A system like original Call of Cthulhu is better for modelling realism, or even the d20 Call of Cthulhu does a pretty good job of this. Shadowrun is not about realism either - but it needs to be able to model its universe played in, which it does pretty well. But the system can be a turn-off for many players.
So, in a nutshell, welcome to the boards, glad you're here, but Shadowrun is not the end-all and be-all of modern game systems.
Good gaming!