>They can all be great language designers, but their approach to compiler construction is needlessly overcomplicated.
Actually Lars Bark and team are not "language designers". Smalltalk (Strongtalk), Java (Hotspot), Javascript (V8), all have been designed as languages by other people.
They are world reknowed experts in compiler design.
JIT is a totally different beast from a simple pipeline compiler. You should have known better. Anyway, you evidently do not know what you're talking about. Consider you trolling unless you can show your compiler code.
As for the rest - yes, compiler construction is not their main research topic. They can all be great language designers, but their approach to compiler construction is needlessly overcomplicated.
A view of a compiler as a chain of stupidly trivial passes, ideally expressed as term rewriting, is not very common among the researchers, but so far it yields the best results.