I wonder is the sheer volume of water used to cool, might explain its lower temperature. It would be interesting to know if it's a turbine efficiency measure, an optimal operating temperature stability measure or whether its just based on a design formulated in an age where energy was relatively cheap or some other reason yet mentioned.
I did a bit of Googling and came up with a few articles that may be of interest though they differ slightly in that they seem to largely focus on using gas turbine fired waste heat to power secondary steam turbines, rather than steam heat recovery.;
Coal company to build western Downs power station - ABC News (Australian Broadcasting Corporation)
CS Energy: Glossary
Cogeneration-Combined Heat and Power (Electricity) Generation (Research Note 21 1998-99)
Australian Coal Association
http://www.futurepundit.com/archives/002148.html
http://www.newscientist.com/article/dn5039-system-converts-smokestack-heat-to-electricity.html