Totally character dependent imo.
It really depends on their options. Doesn't matter how much you want to rushdown with say Ganondorf. He doesn't have the tools to do it well.
You can express yourself in many ways in fighting games then just general play style. Tricks and different set-ups are a great way to differentiate yourself and express your creativity with a character. But generally the best way to go about expressing yourself with a character is to FIRST pick a character that aligns with what you want to do in the first place. Otherwise you just end up fighting that characters design instead of fulfilling the actual goal of trying to expressive/creative.
After playing a bit of Zard and DK, I have come under this theory of Punish characters and Neutral characters.
See, playing with them, you have little control over what happens in neutral, but you have a ton of control over what happens when in advantage (this goes for basically the entire cast, but more-so for them, with DK's "ding dong" (what a stupid name...) and such, and Zard's throw combos and juggle potential with wing-invincible Utilt Usmash and Head-invincible Uair). The goal with these characters is to get their advantage started and to never let go of it, To try to perform a ToD. These characters are of a punish type (ZSS, Ness, Bowser, DK, Luigi, etc...) and they thrive in advantageous situations. The art behind this is to perform a ToD, on various characters with differing weights, fall speeds, hitbox sizes, 3 frame Nairs or combo breakers, opponent tendencies, further pushback due to percent and knock back, recoveries, ledge options, juggle escape options, etc... trying to perform a ToD is a mountainous goal and one to be honored if achieved.
Neutral-type characters like Pit, ROB, toon link, Villager, sonic, link, marth, etc... controls the battle and makes the opponent do what they want. The art of them is to not get touched. This can prove to be difficult when the opponent can PS w/e aerial and punish immediately, roll to mess with spacing, use burst options, or plays footsies better than you. You can see the art in neutral based on the pacing of the match (slow and methodical vs fast and crazy marvel DBZ active style), the spacing battle (if it's an unclear scramble, or space-consuming battle of territory), etc...
The thing is, it's a spectrum and some characters can somewhat do both like Rosa, bayo, sheik, fox, and other top tiers.
Just a wild theory.
I say yes. Anything that requires daily practice and work is an art. It doesn't have to be a pen or a paintbrush. Everything worthy requires skill and hard work, even being a decent person.
Hey, being a good person is an art, then. :D
Not necessarily. Cleaning is something that can always benefit from improvements, but I wouldn't call it artistic.
I think the answer is yes and no.
With any character, there is more than one way to play them. Some let you play however you want and reward you for it, whereas others are a bit more linear where though you can still play however you want, there is a clearly optimal strategy which will yield better results in the long run.
So with most characters, one strategy will be more optimal than others, but with very few of them will the difference be great enough to force you to switch.
My advice: play however you feel the character should be played. But, should you choose a suboptimal strategy, be aware that your results may suffer as a result.
Playing as D3 is pretty limiting in terms of the neutral. Few neutral tools and limiting mobility to skewer his neutral. However, his advantage state (throw combos, juggling, space consumption, and ledge trapping) is pretty good. I think with this breadth of options in advantage allows this aspect of his play to be expressive.
Maybe characters are expressive in different states of the game (I think my wall of text above describes this too).
If you're playing as Greninja, yes
:/ I personally don't care for watching that frog move.