Short answer
You can have a great design that doesn’t make something easier, because I think “great” and “easier” are both dependent on the context in which humans and material things relate to each other.

Long answer
Good design, depends on a definition of “good”. That is probably a book-length, philosophical discussion which would distract from an otherwise interesting question about how design prefigures the future in numerous ways (making things easier, harder, riskier, safer, obligatory or proscribed, etc.)

The view of some sociologists (Schatzki 2002; Shove et al 2007), is that human activity shapes material entities by relating to them in different ways: causally, intentionally, spatially, constitutively and so on. Through our ongoing actions, we continually alter material arrangements which in turn, “act back on us” affecting our future activities. So humans both shape, and are shaped by their designs.

If things (humans included) are contingently related to one another, it is difficult to imagine a scenario where a design makes a particular activity easier without also affecting those relations.

For example, pedestrian bridges make safe road crossing easier by isolating pedestrians from vehicular traffic, but they also make criminal assault easier by spatially confining the victims. Five types of relations between people, bridges, cars and traveling can be described:

• Intentional — pedestrians want safe passage to their work
• Causal — traffic congestion causes pedestrians to use bridges
• Prefigurative — bridges make safe road crossing easier
• Spatial — bridges situate pedestrian in clear view, elevated and isolated from traffic.
• Constitutive — “footbridges” constitute the activity of crossing the road and vice versa, just as its name implies; one is essential to the other.

So, is a pedestrian bridge a good design because it helps people do what they need and want to do in a way that’s easy?

One can imagine a different set of relations established through the activities of extortion, suicide, traffic enforcement, etc. with varying degrees of ease, difficulty, risk, safety, etc. for different things involved (including people). It is ultimately dependent on the context. The interesting part of the “activity-centric” view, is that the context is derived from the same relational web of activities and material things I describe as mutually shaping one another.

Relations between things are not neatly segmented according to their activities as I’ve shown here. They are thoroughly enmeshed together. But from this simple example, you can see that criteria such as “meeting needs” is not as self-evident as human-centered design methods often make them out to be. If contemporary social theories have anything to add to designing, it is that we must look at the dynamics of practices (larger sets of bundled activities and their contingent relations, meanings and identities)—and not merely arbitrary sets material things, humans and needs when it comes to judging good design.

References

Shove, E., et al., 2007. The design of everyday life. New York NY: Berg. Schatzki, T.R., 2002. The site of the social: A philosophical account of the constitution of social life and change. University Park: Pennsylvania State University Press