« An activity will be pursued only if its benefits are equal to or greater than the costs ».
If a function can be performed in 2 s in ArcView, QGis, Udig or Mapinfo and it takes 20 s in a web maping applications, the web maping applications will for sure not be used.
The important thing is to evaluate the ratio Cost-Benefit and not only the cost or the benefit. Typically, a complex wizard can be proposed if the benefit for the user is very high. But, if the benefit is low, than the wizard will simply be ignored.
Source: « Universal Principles of Design » from Lidwell, Holden and Butler