A lot of installers these days assume you’re connected to the Internet. This is especially true of Microsoft’s installers. Despite having produced a wonderful (genuinely) installation famework (MSI) Microsoft still insists on distributing a thousand other installation methods, each with subtly different command line parameters. This invariably makes life a pain if your job involves doing automated installs on machines which are specifically not connected to the net.
Most recent example of this is the Silverlight Tools package. This is a 33MB download, which still falls into the “wait a few minutes” category for most people. Despite this they still insist on downloading a file as part of the installation (only one file mind).
In almost all of these cases there’s a simple workaround – but why not make life a little bit easier and use a consistent offline installation method for everything?