It's not quite that easy though.
For sensors where we already have a UI of some kind, it shouldn't be all that hard to add support for them, although technically they should already be working if they're Z-Wave.
For sensors where we don't have a UI, a lot of work is required from our side and in as much as we're planning on supporting many more types of devices, it's going to take time, especially as we have no less than five different UI's that we need to support for each type of device.
The Z-Wave Alliance might be making claims along the lines that Z-Wave branded products are just supposed to work, but it couldn't be further from the truth. Have a look at anyone else who just launched a home automation gateway and tell me how many devices they support. Take Wink as an example, they have an extremely limited list of support devices of all of five device types. Revolv wasn't much better, although they seem to be adding more and more things, just as we are. Even SmartThings doesn't support everything out there. The only company that has extensive device support is Vera, but they have a half a decade on everyone when it comes to how long they've been doing this.
I'm not trying to make excuses here, I'm simply trying to explain the limitations and why it's going to take us time to support a lot of things. It doesn't mean we don't want to and we're trying to figure out ways of making all of this easier to do.