I do appreciate the addition of blackstone which can be found in the nether
now I can make my roads in my worlds look like they are made of tarmac or asphalt, instead of cobblestone which to be honest doesn't look all that great as it is the same shade of colour as regular stone, just with a different texture.
I do wish that we had a more brownish version of cobblestone to make it look like the roads are dirty and covered in debris, dust and soil, which they generally are.
And about this guys video (wattles) yeah a blackstone base in the nether would be really cool.
But there are so many more designs this material could be used for, even checkerboard slab flooring thanks to also quartz.
So far the only thing I've really done with blackstone is use the polished version to make a kind of leather sofa (edit: that's not to say I don't think it has a lot of uses - I just haven't needed it yet) :
For a checked black and white floor I prefer polished basalt, which goes nicely with quartz pillars. Personally I think blackstone looks a bit too rough to alternate with quartz. In the past I've used black concrete but it's a bit intense.