That works well until you have kids running around... You going to put rechargeable cells in that Elena of Avalor wand your 4 year old chases the dog with? And her talking unicorn? How about all the light sabers?
In my experience, most of those types of toys don't go through batteries fast enough to justify a NiMH - they'd be in there for years. Invariably one of the kids will wind up mixing NiMH/LiIon/Alkaline in a toy, then the rechargeable winds up in the recycling bin a year later.
Fast forward 3 years, and your "infinite" AAs are all gone, lost, or in near-permanent use somewhere you can never identify, and you've wasted all that money.
In a few years when the kids move out and, and the number of battery powered gizmos is down to a manageable number, I'll try it again - until then, Amazon Basics AAA/AA are my friend.