You're reading the rule for melee attacks. The rule for ranged attacks is the sentence before that and is much less absolute (B365):
If you are making a ranged attack, you have a penalty of −2 or the weapon’s Bulk rating, whichever is worse – and if you took an Aim, you lose all of its bonuses.
So you can have an adjusted skill for shooting in excess of 9, if you're really good, you're using a suitable weapon (i.e., not too Bulk-y), and not relying on Aim to improve your skill.
But often, you don't actually want the Move and Attack action
The Move and Attack action is not necessarily the correct action to choose to model what you're wanting. It may be the wrong action to take. If you want a truly skilled shot, you need to pause for the briefest moment, shoot, then keep moving.
The thing to keep in mind is that many combat actions you can imagine aren't a single GURPS action — because they're not a single second of time. GURPS combat round default is one second (B362–3), which is very short. This isn't a game where you normally do multiple things during a round — normally, you can spend several rounds setting up and/or executing a single component of your overall combat tactic.
In another game these might be modelled by a single action, but in GURPS, the normal thing to do is take separate consecutive actions. Moving and fighting in a single round is not the norm in GURPS! Notice how just shifting your posture (B364) or even drawing a weapon (B366) is an entire round — that's the granularity of time we're dealing with. It can take quite a mental adjustment from other games to GURPS, to shed the idea that every turn taken must be damage-dealing, and begin to build player skill with GURPS combat.
So for your ace shooter to be really ace, they know (because they're an ace) that fully leveraging their skill is achieved by very briefly pausing to snap off the shot: that is, you take three actions in three turns: move turn 1, fire turn 2, continue moving turn 3. Give it four turns and you can even Aim!
There are some GM options that adjust or remove the penalty
There are optional rules or Advantages that a GM might add to their campaign to model a more cinematic game or a more fantastical setting. As usual these are strictly GM options, since they're tools in the larger GURPS toolbox rather than core rules.
High Tech provides a GM option in the Appendix (p. 249) to change how the Gunslinger Advantage (B58) works, if they want a more cinematic wild-west shootout dynamic in their campaign. It changes the rules for calculating the penalty from Move and Attack to make it easier. It changes a lot of other rules to make gunplay easier and more effective/appealing too.
(This same optional rule appears on page 15 of the Gun Fu PDF mini-supplement.)
Martial Arts* adds a lot of optional rules and character options that interact with or outright change Move and Attack. One example is the Heroic Archer Advantage (p. 45), which affects Move and Attack much like the altered Gunslinger from High Tech. As an example, Heroic Archer is a option available by default to the Scout in GURPS Dungeon Fantasy RPG — but it's available to only the Scout template, making it uniquely part of being a skirmishing archer character in that genre of play.
Ultra Tech (p. 150) lists as equipment the Gyrostabilized Weapon Harness (think of a Steadicam, or the M56 Smartguns operated by the Marines Vasquez and Drake in Aliens), which cancels Move and Attack penalties.
As you can see, the options to directly reduce the penalties of shooting with Move and Attack are few and explicitly in the domain of GM worldbuilding and GM campaign-building. If you're playing in a suitable campaign and setting then your GM may already have these options available or “turned on” and you're good to exploit them, but if not then you're playing in a more realistic (or lower-tech) game and the usual tactical patience is the way to reduce your shooting penalties.
* Despite typical associations with the term “martial arts”, GURPS Martial Arts is about historical and modern combat (i.e., “martial”!) arts generally, not just Western ideas of kung-fu and such. It's a general campaign resource for adding rules for additional detail in combats and types of combat training.