At least in the future they'll be able to stick to "if it's not certified by us..." for customer support, which was likely the original impetus (along with a desire to cut off cheap alternatives to their devices).
I'm not mad at this at all.
I am. Because it is a way to extort money out of other ZigBee participants.
No, it is not. They have two options - have their own standard or support other ZigBee devices. This has not been a problem with another similar standards like KNX.
but I imagine supporting cheaper third-party devices is becoming a headache
It is not about supporting some cheap third-party devices but other ZigBee devices that Philips claims to support.
Also, want to point out that philips is not "extorting money" from other companies - they can choose to enter the "friends of" program to make the general consumer feel better, or choose not to, at their discretion.
The class of user that realizes any zigbee bulb will work with a hue hub is already technically proficient, and will more often than not be willing to take on any associated "risks."
If you want an analogy, then it is similar to the case where MS Office would refuse to open ODF documents from another office suites and then after uproar would only support documents from friends of Microsoft.
Oh wait it can't (if it can because your wiring is crap and the protection devices are not working you have much bigger problems)
And of course it's not a software issue
Of course it's not. You weren't talking about one, you asked how a LED lamp can burn your house down. It can.
Personally, I can't see how someone could legitimately blame Philips for a Hue-connected-but-unsupported third-party bulb starting a fire, but I don't doubt some will try.
Funny thing though, but that AC/DC converter is manipulated by firmware activated by a wifi protocol. If the fire only starts when the converter is activated into its highest conversion rate in a particular sequence by certain commands sent across that wifi protocol and those commands are being chosen by a user of an app on a mobile device two rooms away, is that a software issue? It's certainly a gray area.