Think I've said this before, but it really irks me when people insist on "moveset potential" being a qualification or a point in someone's favor. Anybody can be made unique with enough effort; It's just something Sakurai does, not a requirement. Either way, I don't think Nintendo cares that much compared to the profitability of the character. It just comes off as meaningless at best and pushing personal opinion as fact at worst.
I think this mindset comes from Smash 4. You see, when Smash "speculators" (can't believe im saying this) were starting to talk about characters, it tended to be "which notable Nintendo Characters are left", which meant the likes of Ridley and K.Rool were heavily disscussed. Mega Man was obvious so nothing really changed after he was confirmed, Wii Fit was seen as just your standard "lol Sakurai is so random" character.
It was Rosalina that really put this narrative into play. When people were thinking of the next Mario character, people's minds went to Toad, Bowser Jr, and Waluigi (and maybe Paper Mario) due to their seniority, legacy and popularity in the Smash fanbase AND general Nintendosphere, so to see Rosalina be chosen was a shock to many. Rosalina was NOWHERE as requested as those 3, was far more recent and had less prominence in Mario as a whole (she was notably reduced to a minor role in Galaxy 2, and only truly flourished in MK when it came to Spin-Offs) people had a hard time trying to reason why she was the one chosen (Bowser Jr stopped being prominent in Smash 4 Speculation for the most part, up until the ESRB Leak) and people noticed how her moveset stood out, and let people to believe Rosalina's moveset idea was the main reason for being chosen.
This only was further reinforced to its logical extreme with Robin's reveal. People believe that Chrom was going to be the chosen one due to him being basically FE's latest "poster boy" and the token Lord of the most recent installment at that time, so to see Robin was a surprise to many (ESPECIALLY due to the infamous "Gematsu Leak" which supported Chrom)
and the reasoning was............basically Chrom felt too vanilla and Robin was easier to picture as his own full-fledged fighter:
At the end of the day, Chrom would just end up being another plain-old sword-wielder like Marth and Ike. Compared with other characters, he lacks any unique characteristics.
Conversely, when the idea of including Robin came to mind, conceiving the character was so easy that I immediately saw how it would work. From standards to specials, grabs to throws, all aspects of his moveset just fell into place. Not only did he possess characteristics unlike other fighters, but he also captured the essence of the Fire Emblem series. It was perfect!
In the end, if a game isn't fun, then there's no point. Of course, it would be really easy to make a game by churning out a ton of similar characters, but that's not how I produce games.
Although it's not that "Chrom wasn't unique", but rather "Robin was faster and easier to figure out a moveset for and i can't be arsed to slowdown this game's development too much because jesus christ im making basically 2 games for 2 different systems for the same year"
This narrative also happened because of Smash 4 being more brazen and less strict with its movesets compared to earlier games. Smash 64 was clearly built with basic character types in Mind (Mario was the token Shotoclone, DK was the token Heavyweight, Falcon was your basic rushdown character) but slowly became less basic as the series went on, and the newcomers stood out more with unorthodox characters that were the exception to the norm like Zelda and Shiek or R.O.B, but in Smash 4, they BECAME the norm, but it seems most people didn't catch up to that.
It feels to me that the more wacky movesets we got today for Newcomers are a result of Sakurai simply having more time, budget and resources to give the characters he choices a much more proper treatment, rather being chosen just for the uniqueness.
For example, K.Rool made it in because he was a prominent important character from a highly successful game series, whose popularity allowed him to stay afloat for years after its retirement, not because he has a steel belly that can reflect and tank damage.