Smithy is ruler of another world, uses a hammer as his weapon, can shapeshift, and with the four members of the gang besides Exor (counting the Axem Rangers as on entry) he leads a Five-Man Band that seek the Star Pieces...could Smithy have been intentionally designed as an Evil Counterpart to Mario?
Smithy is a blacksmith, Mario is a plumber. Both are blue collar occupations. Hmm...
The similarities go further: Both of them sport awesome facial hair of some kind (Mario a mustache and Smithy a beard).
Without the Star Road, no one's dream can come true. That also includes Smithy's wish of ruling the Mushroom Kingdom.
However, Mario and his party's actions end up fulfilling several of the unrealized dreams on Star Hill, most notably reuniting Mallow with his family. This could possibly point to An Aesop of working hard and perseverance matters more in realizing one's dreams as opposed to a magical wish-granting star.
The scenes with Gaz and Geno parody Fixer Sue with how Geno usurps Mario's role and how Gaz treats his custom doll with more respect than Mario. Geno (or rather, the spirit inhabiting him) is wildly popular, reasonably developed, and useful on the front lines, which is a welcome bonus.
The mass produced Machine Made copies of Smithy's lieutenants are of lower quality than the originals and are much easier to defeat as a result (though some of them have some slightly improved stats), implying that Smithy is sacrificing quality for quantity so he can quickly build a new army for a second invasion of Mario's world.note Specifically, Smithy is not taking into account how powerful Mario and his party have become since the beginning of the game, and as a consequence, has not scaled the Machine Mades' stats accordingly, making them very easy to take down. In real life the question of "quality vs. quantity" informs most manufacturing industries and it's a common belief that mass production results in lower quality products.
Giving a specific real life comparison, it's like how many people don't like redecos of Transformers toys because they use the same mold, and one of the problems that can happen is that the molds used gets damaged so future versions of those products get defects. the molds may be getting damaged from making so many copies, or he's just using a material of different quality for each of them
It may seem weird that Mallow gets the Star Rain spell instead of Geno, when Mallow's other spells are weather-based and stars are Geno's specialty. However, going by Final Fantasy conventions, Mallow is a Black Mage, and Meteor is usually one of the ultimate black magic spells. Another name for a meteor is a "shooting star," so Star Rain is just what Meteor would look like in the Mario 'verse!
All of the characters have Playing Card Motifs when they use their special attacks: Mario has spades, Mallow has clubs, Bowser has diamonds, Peach has hearts, but Geno has... stars. But Geno isn't from the Mushroom Kingdom, he's an otherworldly being, so of course he doesn't fit with the card motif!
After the first boss fight against Bowser, a cutscene with Exor descending from the clouds and destroying the Star Road as he falls straight into Bowser's Keep is shown. After the title of the game disappears, the Star Road's fragments AKA the Star Pieces are seen falling. It's an easy-to-miss detail, but if you line up Bowser's Keep to the rest of the World Map, you'll notice that the falling Pieces' directions indeed line up to the locations you find each of them throughout the game.
"Then we could get rid of all wishes, and create a world filled with...WEAPONS!!!" From a metaphorical perspective, Smithy's speech can be considered foreshadowing because...
The main theme of the Final Fantasy series was changing from Medieval Fantasy to Sci-Fi.
Squaresoft would leave Nintendo and go to Sony.
The main trend of video games was changing from "kid-friendly" to "mature audiences".
Smithy is vaguely mechanical-looking. The design of the battleground of the second fight against him features a number of Smithy-esque heads littering the area. How many more Smithies are there? Who is making them?