Well, what's the worst that could happen? ADE/OAS or other unpredictable immune problems from constant tinkering and perturbation? Driving the virus to evolve yet another immune escape variant which might be much more virulent? These risks seem insignificant compared to not boosting against a virus with a CFR that's now about 1.5x the flu.

Actually, from what I have seen of the initial Omicron booster trials, it's probably the case that they're simply unable to stimulate much production of updated/modified antibodies, which is making it impossible to demonstrate any clinically significant effectiveness against the disease. But now they won't have to!