Why is a home fiber coection asymmetric?

I recently switched from an ADSL to a fiber coection and was surprised to see that the bandwidth is asymmetric (1 Gbps down / 250 Mbps up).

While this is understandable in ADSL, I do not understand why fiber at home is asymmetric as well? It is not a limitation of the technology (I have symmetric fiber at the office, and always had)