I see that you don't really understand what's needed for real IDE integration. Please, understand one of the main reasons of Apple creating Clang... (hint: because the GCC guys wouldn't take their patches to improve Objc-C & add facilities for IDE integration fast enough)
Clang was easier to integrate with an IDE than GCC, and I strongly believe (after seeing what apple showed yesterday) that swift integration is even simpler.
( They must have made a new LLVM front-end to embrace IDEs equally or better than Clang )
So no, it's not silly to try to design better to have a better integration with an IDE that you control too.
"Ruby, Python & co are well integrated into many third party IDEs" perhaps you're not familiar with the level of IDE integration we're talking about here.
Most (if not all) IDE's Ruby and Python integration is BS.
We're talking about real AST-based highlighting and suggestions, auto fixes, autocomplete for all APIs available (AND your own custom modules), integration with the debugger and the build system, and in Swift's case also integration with the REPL, LighTable-style live-variables and Brett-Victor-inspired live coding environment.
Clang was easier to integrate with an IDE than GCC, and I strongly believe (after seeing what apple showed yesterday) that swift integration is even simpler.
( They must have made a new LLVM front-end to embrace IDEs equally or better than Clang )
So no, it's not silly to try to design better to have a better integration with an IDE that you control too.
Cheers.