Glad you like the font!

I appreciate that on some devices, FreeMono might be too thin.  But this is why we have different fonts.

The main effort of this project is to produce an adequate family of fonts that supports as many human languages as possible.

As to tailoring the weight of the fonts for different devices:    Already there are 12 faces, you are proposing to add another 2 (assuming the medium weight would also get an oblique version).  There are nearly 2500 characters in MonoBoldOblique alone, nearly 6800 in Mono Normal.  Many of these would require manual adjustment if the weight would change.

This would be a bigger step than you imagine, and we just don't have the resources, and it isn't toward our main goal.

That said, it's not a bad idea. 

Sure, somebody could make another free software project, restraicted perhaps to Western alphabets, based on FreeMono. .  They could do whatever they like there!  And if all parties agree, the projects could be merged sometime in the future.

Thanks!