The biggest barrier to using wearables is their limited battery life. Some smartwatches can be used for a full day or two on a single charge, depending on the brand. Others exhaust their battery in less than a day of normal use. You need to charge it daily to ensure continuous usage.
Another disadvantage would be the cost. The price difference between a smartwatch and a mobile phone is not that much. Some users would find buying a smartphone a better deal because it has more advantage in terms of screen size and storage. Moreover, certain smartwatch models are not water-resistant and have a shorter lifespan than mobile devices.