In my experience, the assumption that "most people won't notice" is usually incorrect.

The fact of the matter is that people usually do notice, if only subconsciously. If you show someone a clip from a Disney movie and a clip from a Hanna-Barbera cartoon, they will be able to tell that the animation quality is much crappier in the latter. They won't be able to tell you why, but on a visceral level they will be able to feel the difference. [1]

This visceral feeling of "quality" is what gives Apple's brand such cachet. Sure, their skeumorphism can be tacky, but it's never slapdash. Their apps always run at the highest framerates, and their touch interactions and animations have always been tweaked to a level that their competitors can't match.

Now, if you asked someone what the difference was between Mobile Safari on an iPad Mini and Chrome on a Nexus 7, no one would say "the scrolling is much smoother on the iPad, and the variance in framerate is much lower as well, which contributes to a feeling of responsiveness and playfulness", but those features still contribute dramatically to the "feeling" you get when using one of the two devices.

Now, sometimes it really doesn't matter. The example in the OP seems particularly silly. However, don't underestimate the value of "bumping the lamp" when it comes to design or interaction development. People will notice.

[1] The answer to the "why" has many parts, but mostly involves the fact that Disney animation runs at 24fps while HB cartoons ran at 12fps or even 6fps. Disney animation involves characters that are carefully articulated and that move realistically and with a sense of weight behind them. Also, the general quality of animation and camera work was just better -- look, there are a lot of reasons. They all add up to the difference between Scooby Doo and The Little Mermaid.

I see where you're coming from, but to me all you're writing is an excuse for unlimited perfectionism. Perfectionism rocks of you're among the lucky few who're in a situation where you can get away with it. In most circumstances, however, there's a product to ship, with the end of the money in sight.

I mean, in terms of the 80/20 rule (the last 20% of quality costs 80% of the time), we're not talking about turning an 80% thing (i.e. typical in-house enterprise software) into a 90% thing here. Hell, even going for 95% is something I believe we should all go for, and fight our colleagues, bosses and project managers, and customers for. But the OP's example is more like turning 99.5% into 99.8%.

I read this article and immediately jumped into the comments, praying that there would be a comment like this - thank you. Very well put -- details are what separate an amateur from a master.

To add what little I can to this, the reason that drives me to go to these lengths is the craft. Design, like code, is a craft. A good craftsman just does not leave mistakes in their work purposely. Whenever I do this it slowly drives me crazy until I either go back and fix it, or drop the project entirely (if there are a lot of mistakes and/or things I don't really like), usually citing some reason like 'it's too messy' or 'i lost interest'.

For me, design and programming are not all about a/b testing, 100% time efficiency, etc. A lot of it is about art -- making something you know is great and shipping it. When you know something is wrong with your work as an artist, it will bother you until it's fixed.

As a coder & semi-pro-designer I reached the conclusion that little bad/ugly things add up (or even multiply!), eventually resulting in something that looks bad/ugly even to average-joe on a greasy sunlit screen. If a badly scaled rounded rectangle is mixed with bad font scaling/rendering and on the next iteration a bad color-scheme decision, the ugliness of the whole is more than the ugliness of the parts added up. It sounds vague and artsy but that's how I find it: "harmless" little ugly things add up to an aesthetic carnage. Yes, it's "premature optimization" if you look at things like a programmer, but the "designer mind" can't really separate "optimization" from "just getting things to work".

A fundamental point IMO that you are missing is that there are a few differences between a work of art and a programs UI.

1. A work of art is created by definition to be beautiful. While a beautiful UI is awesome and definitely something to strive for, it is not the end goal.

2. A UI can be changed after its release. Unlike art, you can release a UI and then later change details that are important.

3. Most companies do not have the manpower or time to actually get to the place where the entire product is pixel-perfect. pg's mantra is: "release early." This means that not everything is going to be perfect and you have to decide what corners can be cut and which cannot. (You cannot simply state, I am going to cut NO corners).

4. A UI is likely to change. When you first release a UI you dont really know how it is going to be used. Therefore, as the OP suggests the improvement from 95%-98% really does seem like a pre-optimization.

That said, the UI should make the experience easier in that it aids the function. I would take it a little beyond that where you want something attractive to look at, but it doesnt necessarily need to be in the v1. As the UI matures over time beauty in design becomes a more important goal.

Awesome comment. And thanks for the info on the Roger Rabbit bit, that's fancinating. I agree with you that pixel-perfection seems like a waste of time to a non-designer ("who the heck is going to notice?!?!" is the common refrain), but I think of it like this: no, people probably won't notice one, maybe two deviations from an ideal asthetic or consistancy. But those add up fast, and pretty soon you have an interface that's a mishmash of font sizes, colors, textures/no textures, etc., and people do notice. They notice because a competitor has gone the extra mile and paid attention to detail, and now they're crushing it and you're looking like a second-rate, half-baked wannabe. Design quality is every bit a competitive advantage in not only consumer software, but even enterprise software now.

That makes a lot of sense. I'd not heard about that particular phrase before - but I can see exactly what you're talking about.

When I inspect a cathedral, that is perfectly considered at every level of detail, I know more powerfully than at any other time that life is worth living.