How to write good content as a mediocre UI/UX Designer – [Design Case Study]

What was the point of this? To rant?

Anyway, I ran into this issue where I have hundreds of people visiting my website daily, but any web dev complains about my UI-

"Fascinating concept, but site looks like its from 2000"

Does it matter what the trendy look is? I believe as long as its useful, it should be fine? Idk if I should care.