Eric Gunnerson, member of the C# compiler team, explains how language features are evaluated:
"So, we decided on the additive approach instead, and worked hard to keep the complexity down. One way to do that is through the concept of minus 100 points. Every feature starts out in the hole by 100 points, which means that it has to have a significant net positive effect on the overall package for it to make it into the language. Some features are okay features for a language to have, they just aren't quite good enough to make it into the language.
A feature like expression filters in VB is in this bucket. Yes, being able to put a condition on a catch is somewhat more convenient than having to write the test yourself, but it doesn't really enable you to do anything new."