EAL criteria are so operationally restrictive that useful work is effectively prevented from happening. No one needs worse security, we need better security.
A number of us have conformed to higher ones on a budget with small teams. The highest one's are indeed a ton of work to accomplish yet there's been dozens of projects and several products with such correctness proofs. They figured by the 80's they needed their certified TCB to be re-usable in many situations to reduce the issue you mentioned. Firewalls, storage, communications, databases and so on all done with security dependent on same component. Modern work like SAFE (crash-safe.org) takes this closer to the limit by being able to enforce many policies with same mechanism.
So, your claim is understandable but incorrect. Useful work repeatedly got done at higher EAL's. It continues to get done. The real problem is (a) bad choice of mechanism for TCB and (b) bad evaluation process. Most of us skipped high-EAL evaluations for private evaluations instead by people working with us throughout the project. Saves so much time and money while providing even more peer review.
They really need to improve the evaluation process itself so it's not so cumbersome and update their guidance on best mechanisms for policy enforcement. Probably sponsor via funding some of them like they did in the old days. Fortunately, DARPA, NSF, and EU are doing this for many teams so we can just leverage what they create.
