"Approximately 63% of large software projects are over budget and
the top four reasons rated as having the highest responsibility were related
to usability engineering." (Nielsen, 1993)
Save development time
"Speeding up development is a key goal for integrating usability
effectively into product development; one-quarter delay in bringing a
product to market may result in the loss of 50% of the product's profit."
Reduce maintenance costs
"It has been found that 80% of software life cycle costs occur during
the maintenance phase and were associated with "unmet or unforseen"
user requirements and other usability problems." (Nielsen, 1993)