There's nothing inherently insecure about a smart lightbulb. With studies like this proving the danger inherent even in a 100% perfectly secure bulb, then yes, people likely won't attach them to secure networks. _Without these studies_, they would, because nobody would know of any dangers.
You're thinking too current. There's no reason why an "industry" smartbulb won't exist in the not too distant future, with hardened security and professional use cases. This study is flagging up that even with hardened security there are new attack vectors.
