Your ratings are... unusual.
The thing is that the value of affinities decreases as you go up, so having one sky-high affinity and the others in the dirt isn't as useful as a balanced set, even if the balanced set doesn't have as high of a total. Having an affinity of 50 increases damage by 100%, while having an affinity of 150 decreases it by only 33%.
For example, say you're facing a boss that uses all six elements equally with attacks that do 1000 damage each time regardless of defenses. Take a character who has a 500 in Fire and 20 in everything else, and a character who has 100 in everything.
Character A takes:
200 damage from the fire attack (1000 x .2)
5000 damage from all the other attacks (1000 x 5)
Character B takes:
1000 damage from each attack (1000 x 1)
And just for the hell of it, take a character who has 200 in Fire and Cold but 50 in everything else:
500 damage from the fire/ice attacks (1000 x .5)
2000 damage from everything else (1000 x 2)
So in the end, character A takes 25200 damage total and character B takes 6000 total. Character C takes 9000. The closer to being totally balanced your affinities are, the higher the weighted rating will be (of course, it's also affected by how high your affinities are total).
I'd also make the argument that by the time you get her, you should easily be able to pump her natural affinities up to at least 100 without debting yourself too much in SKP.
This is valid, but you can't really compare a character that joins on 14F to a character that joins on 1F that way, because lack of skill points on 1F is a party-wide problem, it's not unique to any specific character. That, plus the fact that by 14F, assuming you're distributing resources equally, 1F character will have as many skill points invested in affinities as 14F, so if you're trying to compare the characters during the time they're both available, it's a moot point.
And while others will probably be seeing a natural 150-200 by this point with those same costs, keep in mind that nobody else will have a natural ~350 either without a seriously large investment.
That's because it's a rating for affinities as a whole, not individual affinities.