- A good IDE, like Eclipse for Java.
- Good multi-threading.
- Standard and rich GUI.
These are very superficial reasons against a language. IDEs are a matter of personal choice. Multi-threading is being worked on, and is of limited use for web apps anyway (even on multi-core processors). GTK2 is pretty good for GUIs and works pretty well across platforms, with a few other choices beyond that.
If I was going to bother moving to a new primary language, it'd better offer something clearly superior to Perl. The kind of stuff that's been kicking around CS departments for a long time, but has barely registered in mainstream languages. Stuff like type inferencing or operators in RPN notation. If the language isn't going to challenge me to learn new concepts, it's hardly worth learning.
"There is no shame in being self-taught, only in not trying to learn in the first place." -- Atrus, Myst: The Book of D'ni.