Probably 80%-90% of 13-2 is its own story. One of the main characters was a side character and largely uninvolved in the original. The other main character is an original character. The enemy is original. The very ending is relevant, but summed up with a little bit extra.
The biggest thing you’re missing out on is the context of random characters from the first game showing up in the second.
Considering the controversial mechanics and the protagonist with trust issues, that opinion is pretty opposite of what I expect to hear generally speaking.
I love the mechanics too. But I found the cast to be pretty relatable either for myself or for people I deal with. I thought the story, particularly Squall’s evolution and internal conflict, to be fascinating and cause for self reflection.
In 7, Tifa and Aerith and interesting. Both anesthetics that are polar opposites of their personalities, and story appropriate too. Aerith in particular giving off major “preacher’s daughter” vibes. But outside of those two, I can’t imagine being able to identify with a single other cast member. I didn’t particularly like the story either after Cosmo Canyon.