Would anyone else find an "I2C 8 Channel Relay Controller" to be a useful product?

I have a project for an Open Source hardware environmental controller.
The challenge I have is some users will want 4 relays and some could have 6 or 7 depending on the customizations they want. I’m thinking in the base design to have a relay controller board (Think the Grove - 8-Channel Solid State Relay without any relays and just having a bunch of grove ports to connect an arbitrary number of 1 or 2 channel relays until all 8 control addresses are used up.) that is part of the base design and people could add extra relays without having to deal with an additional I2C channel or expensive and underutilized module.