Conventional type of vaccines rely on either attenuated or dead virus, no? So with those examples, the external shape of the virus is what is supposed to inform the immune system; if I remember correctly. And I am of the understanding that these family of viruses have a good ability to change or adapt, so that any vaccine (presumably of any type) would merely trigger adaptation, especially in pandemic/endemic conditions due to high viral populations and therefore increased likelihood of advantageous mutation emerging.

In any case, you're right, it is definitely not worth it considering the current variants and the presence of other effective treatments.