Turns out, consumers are more interested in basic wearables than fancy, feature-rich ones.

According to new data from IDC, shipments of wearable devices reached 22.5 million units in the second quarter of the year, a 26.1 percent year-over-year increase. But while the overall wearables market grew, its two categories "traveled at different speeds and directions," the research firm said.

Basic wearables, aka those that don't support third-party applications, grew 48.8 percent from the same quarter last year. Smart wearables, on the other hand, declined 27.2 percent year over year.

"Basic wearables, which include most fitness trackers, have benefited from a combination of factors: a clear value proposition for end-users, an abundant selection of devices from multiple vendors, and affordable price points," IDC's Research Manager for Wearables Ramon Llamas said in a statement. "Consequently, basic wearables accounted for 82.8 percent of all wearable devices shipped during the quarter."

Smart wearables, meanwhile, "are still struggling to find their place in the market," Llamas said, adding that the transition from basic wearables to smart ones will be "slow."

"There is plenty of curiosity about what smart wearables — particularly smartwatches — can do, but they have yet to convince users that they are a must-have item," he said. "The good news is that smart wearables are still in their initial stages and vendors are slowly making strides to improve them."

Breaking down last quarter's results by vendor, Fitbit lead the market as the top wearable device maker, shipping 5.7 million units to grab 25.4 percent of the market. China's Xiaomi, maker of the Mi Band 2, came in second, followed by Apple, Garmin, and Lifesense (maker of low-cost Mambo fitness trackers shipping into China). Apple was the only vendor in the top five to post a year-over-year decrease in shipment volumes, IDC said.