Yeah, not sure how I'd turn it into a general house rule, but anything less than 25XP (owing to its usual tree placement) seems OP.
The same is true for dedication, though. But when the average starting value is 2 for a characteristic, that's actually a discount on the 30XP you'd spend at character creation. Of course then there's escalating cost of accessing new specializations. Suffice it to say, buying up FR at character creation would be a bit of a mess.