I'm guessing Li-ion batteries were always the battery tech used in smartphones, so it might have been harder to notice. I know once I put some Li-ion AA batteries in an old camera I realized I may never need to replace those batteries again.

That's because product designers used the improved performance to reduce package volume and weight.

See this graph of energy density over time:

http://electronicdesign.com/site-files/electronicdesign.com/...

from http://electronicdesign.com/power/here-comes-electric-propul...

You clearly never used a NiCd camcorder.