Even if vaccine prevents serious illness from the current strains, the ADE hypothesis is that the vaccine will enhance illness for future strains.
Also, once you get the vaccine, you don't build up more natural immunity. That's the point. The vaccinal immune response discourages the immune system from mounting a defense to the novel strain, instead it just pumps out antibodies for the Wuhan strain encoded in the vaccination. In the future, if these Wuhan antibodies cannot bind the new strains, the situation is obviously very dangerous, and much worse than not being vaccinated at all.
Also, once you get the vaccine, you don't build up more natural immunity. That's the point. The vaccinal immune response discourages the immune system from mounting a defense to the novel strain, instead it just pumps out antibodies for the Wuhan strain encoded in the vaccination. In the future, if these Wuhan antibodies cannot bind the new strains, the situation is obviously very dangerous, and much worse than not being vaccinated at all.