Yes, I do not like this idea for the most part.

Smaller FCs (like mine) would have a giant disadvantage if you make housing cost solely via FC points. Utilize the price range you have listed, we wouldn't even make the small house price by the time of the update (sitting at 335k FC Points), and I started my FC 2 days after release. It would force smaller FCs to have to migrate to the larger FCs just to have a taste of the larger houses. Also, anyone just starting their own FCs couldn't possibility accumulate that many FC points in a respectable amount of time on their own. No thanks.

Where I do see potential of utilizing FC points in this instance would be to help mitigate the prices, but please do not let it cost FC points outright. For example, 5-50 FC points = 1 gil. But directly towards housing cost, not a direct gil exchange.