>>14027553>>14027590JWST has goad mirror coatings, which is stable and good in reflectivity in the near infrared but bad in the visible and useless in the UV. The telescope will have crap efficiency in the UV.
Working in the UV was incompatible with being a good infrared telescope, because the cold mirror will accumulate molecular contamination, ruining the reflectivity in the UV.
A visible wavelength camera was studied, but lost out to the mid infrared instrument (MIRI). It was probably a good choice because the mid infrared is more unique among current facilities. JWST already has 4 science instruments, which is quite a lot for a space telescope.
