I feel like France not having rifles is a good idea, they had didn't have them then like you said however they still found ways to fight on and utilise what they had... Whilst the game does need to be balanced there needs to be faction differences, so every factions doesn't end up just being a reskin of the other. France not having rifles will 1. Be historically accurate, 2. Make people playing France think of new ways to counter the British rifles.
Then again I may be wrong, but that's just my 2 cents on this.