Actually, there is absolutely no need to use Li-Ion's in the disposals: they could simply use regular alcaline batteries. Furthermore they are preffered due to best one-time capacity.
I said lithium because most disposable devices on the market currently use lithium batteries. But regardless of what kind of battery they use, it's a terrible move to be selling disposables. First of all, just by calling it a disposable you are encouraging people to throw out the device instead of recycling the battery, which is encouraging them to violate the law in most parts of the US. So just by calling these "disposables" you are making yourself an accessory to the dumping of toxic materials in most states.
Secondly, since we have the choice we should be minimizing use of single-use batteries by using rechargeable batteries instead that can be used time and time again, thereby saving valuable resources, protecting the environment from being stripped for these resources, and protecting the environment from the all the chemicals from these batteries. I mean, it's not so bad if people would recycle these batteries, but most people don't, labeling them as "disposable" doesn't help.
I suggest that any suppliers who insist on selling these that they sell them as "single-use" devices, rather then "disposables" and as I said before, provide the customer with a pre-paid package to return the device (or just the battery if they want to take it apart). Doing anything less is irresponsible and selfish.