Smaller sprockets mean less material and a shorter chain. Wow, that's less weight. For the longest time freewheels didn't go smaller than size 14. With cassette hubs taking over it's possible to get a 9T cog in the back. Prices of cassette hubs have come down and can be found on complete bikes these days. This has opened a market for smaller front sprockets.
In the picture you see several small sprockets. From left to ride, top to bottom:
Flybikes - Simple - Flybikes
Terrible One - Fit Bike Co.
S&M - FBM - Snafu
If you run a 44-16, it's time for a change.
BdJ