That's a pretty good point. As far as the average Joe is concerned, any decent knife made of reasonably good steel will do the job. For most people the difference between high performance steels is basically academic. Not so when we're talking about the more discriminate user, however. Even a relatively minor difference in hardness or wear resistance can have a significant impact on performance when you use a blade regularly.

I work a lot with hand tools (traditional crafts) and I have definitely developed my own personal preferences in regard to blade steels. I feel my preferences are based quite objectively, too. For instance, I love laminated Japanese carving tools because the high carbon steel layer is very pure and takes an incredibly fine edge. Then I have a set of chisels made of high speed steel (HSS) hardened to about 63HRc. Which is wicked hard and lasts a very long time. After several days of hard work those chisels will still shave hair better than a disposable razor blade. For a longer blade I would look no further than 5160 spring steel. Good cutting performance and excellent toughness.

Funny that you mention D2. My experience is pretty similar - good wear resistance but difficult to sharpen and won't take a fine edge. Once you move up to higher grade stainless steels the difference becomes less obvious but it's still apparent. My Spyderco's VG-10 will outlast the blades on my SAK by a considerable margin. Comparing VG-10 to 440C there is still a perceptible difference, though a lot less once you get in the range of S30V and 154CM.