The problem is still that their efficiency isn’t really what most people would consider a big leap forward in technology. Plug-in electric hybrids still remain the “gold standard” of what the auto industry needs to move towards in order to truly free people from gasoline. As it stands right now, a hybrid just improves fuel economy, it doesn’t really create the massive shift towards electricity that would happen with plug-in hybrids.
Another problem with traditional hybrids is that they are underwhelming. Typically their trunks are small because they need space for lots of batteries, and the improvement in fuel economy might only be 20-40%, which isn’t that impressive considering traditional engine tech makes those kinds of gains every 15-20 years or so without batteries.
What is really needed is an improvement in battery technology. It’s been said by many people, but until batteries can simply store more energy, the widespread adoption of hybrid tech will have to wait.