In 2005 the hot new Windows technology was .NET Framework 1.1 or 2.0. You can't just dump Framework 1.1's libraries next to the binary and expect it to work either, it needs to be installed properly.
.NET 1.x tho, yeah.
(Yes, if you fiddle with the config file they might work on the .NET 4.0 runtime. But that’s not something a typical user can/will do.)