I hated them the first time I saw them, now I think they're OK.
Same. It'll blow over and people will get used to them, like they have with every update. I am just not a very big fan of change. And besides, I quite like the "ugly" mismatched textures anyway. They've grown on me. But looking at for instance old gravel textures feels weird. Like I said, will get used to them.
I personally like the new textures better than the old ones, the new ones is more appealing to me for some reason.
To be honest I think most people would agree, but they're being held back by a feeling of nostalgia or fear/discomfort when it comes to change, myself included. People will get used to it though. There have been texture changes for many years, they were a bit strange at first but then we got used to them. I think some people are overreacting a bit.
The texture artist must then take into account where the block is probably going to be mostly used for. A normal brick will be used often in large walls, roofs, etc., so it needs a generic, easy on the eye texture with not too many specific details or patterns.
But a jewel block will mostly be used for small accents and decoration. So it doesn't have to be made fit for large buildings (with complicated light maps) and thus can have some special, unique textures.
You made a very good point: most people won't be building giant walls out of emerald blocks. I'd agree, if one were to place only a couple it wouldn't look as strange anymore. It would still look a bit off, maybe, but then again that happens with all Minecraft textures, simply because most objects aren't usually blocks. And obviously because of the limited options you have with this small amount of pixels. I personally don't tend place emerald blocks, so it wouldn't really make a difference for me anyway. It was just annoying me that the example made it so obvious where the light "is" coming from.
They also try to make blocks of noble metals, like diamond and emerald, actually look like huge square juwels. In my opinion the shown emerald texture and color is spot on, making it much more feasible to build for example the emerald city. Also the new diamond block looks much more as an actual huge diamond then just a plain cyan block.
The issue I have with this is that especially the emerald block have a really clear light source. This makes it look like an actual jewel but it also makes it look weird when your light source isn't actually coming from that point. For instance in this picture:
The white triangles on the floor and ceiling don't match up and it's annoying me to death. I like the idea of making them look like actual jewels but I dislike the fact that they seem to be trying to make the side "stick out" without it actually sticking out. It looks off to me.