Question

Why isnt hades worshiped anymore?

Answer 1

I assume since his worship involves necromancy which is look badly upon by everyone else

Answer 2

Religious beliefs change over the years as societies advance and ask more questions about why and how things are. There are in fact religious groups still worshipping the old deities. Some examples of those that still do are, Pagans, Wiccans, and other "witch" religions. The more modern our society becomings to more singular and more powerful the  "god" some worship is. And as these beliefs phase in and out there is the nagging thought of "what will we find that will change our view?"