This may have been said before, but I am posting anyways since there's so many comments here and I don't have time to read them all.
I think I have a way to explain why pixel perfection is a very good optimization that caters to more of a a developer mindset like yourself; it comes down to image compression, and specifically PNG compression.
When it comes to UI elements, the fewer colors you use, the better. This means avoiding things like gradients, or unnecessary colors can have a major impact on file size. It's also the 'art of design' to manage to create a beautiful design without a lot of crappy and needless 'veneer'.
I don't know the specifics of the PNG algorithm, but it can do an amazing job at compressing an image if it's made up of few and often repeating colors (typically it's terrible at photographs, however).
When you apply a scaling algorithm (as exemplified by the post) other than nearest neighbor, it tends to create a lot of intermediary colors that end up hurting the size of the image.
Looking closely at the borders of those buttons, that blur is going to end up adding to the file size because it adds colors that didn't exist before. If you properly 'scale' (which sometimes requires a redraw at a smaller size to get it right), it can have a huge impact (sometimes as much as 2x or 3x).
Oftentimes you can get away with it from a 1/2x scale fairly easily, but you have to remember there are many android devices at a 1.5x scale, and that can sometimes require completely new rounded corners that take advantage of that pixel density.
This is of course anecdotal, but it's not as simple as 'looks' even though I could immediately see the differences between the properly and unproperly scaled images.
I think I have a way to explain why pixel perfection is a very good optimization that caters to more of a a developer mindset like yourself; it comes down to image compression, and specifically PNG compression.
When it comes to UI elements, the fewer colors you use, the better. This means avoiding things like gradients, or unnecessary colors can have a major impact on file size. It's also the 'art of design' to manage to create a beautiful design without a lot of crappy and needless 'veneer'.
I don't know the specifics of the PNG algorithm, but it can do an amazing job at compressing an image if it's made up of few and often repeating colors (typically it's terrible at photographs, however).
When you apply a scaling algorithm (as exemplified by the post) other than nearest neighbor, it tends to create a lot of intermediary colors that end up hurting the size of the image.
Looking closely at the borders of those buttons, that blur is going to end up adding to the file size because it adds colors that didn't exist before. If you properly 'scale' (which sometimes requires a redraw at a smaller size to get it right), it can have a huge impact (sometimes as much as 2x or 3x).
Oftentimes you can get away with it from a 1/2x scale fairly easily, but you have to remember there are many android devices at a 1.5x scale, and that can sometimes require completely new rounded corners that take advantage of that pixel density.
This is of course anecdotal, but it's not as simple as 'looks' even though I could immediately see the differences between the properly and unproperly scaled images.