VB is a very powerfull language and you shouldnt underestimate it unless you have worked on it.
.NET platform is also very powerfull and thats were VB.NET gets its power from , although I is not as good as C++ (C++ is a low level language) and thats why people prefer vb or C# because they can understand the code better.
Now you are right about the program , its not easy to infect someone with this , specially in-this-kind-of-way.
Rats and trojans (backdoors , downloads , droppers) are outdated now.Hackers now tend to use exploiting more that infecting people and making botnets.Although stupidness is something that exists over the years of humankind.
So you are right there are not many chances that this would work very good , but its not because of the language its coded , its because of its whole philoshophy.