Impedance mismatch. Languages don't give the compiler enough semantic information to work with, and some require heavy runtimes. Compilers, on top of having to infer semantic information about the above, aren't able to sufficiently utilize the hardware, either due to constraints on the types of analyses done, or lack of control. The hardware exposes an API too high-level or too unfamiliar to existing compilers.

IMO, the future is bright, because all these layers are being re-thought. However, phrasing this as a debate over programming paradigms is a red herring. If coupling data and behavior is a useful mental model, we ought to accommodate that while giving the compiler more to work with.