It is pretty easy to drop things especially if you’re a clumsy person. If you were to go outside whilst wearing wearable technology, if it would start to rain it could possibly break because it got wet. It could also be a hazard due to it being electric, it could possibly lead to a shock. A way to design around those issues is to put some sort of casing that protects it from water, breaking from an impact of a fall, or just not wearing it outside in general.
(English isn’t my strong suite, hope this helps?)