Ulysses was written in Paris, where James Joyce lived, and was published in Paris by the now legendary Shakespeare & Co. The US and UK banned it for being obscene.
When I don't know, I ask and don't judge (and lacking omniscience, I don't judge anyway).
It's completely irrelevant where it was written, where it was published and where it was banned, I'm talking about how it is seen today. It is possible I am getting this wrong -certainly possible, since I'm taking this impression from English speaking sites like this, that I attribute to the US what should be attributed to England -, but I have seen no argument so far that even strives the point I made.
What is your question? If you just want to know why Ulysses is seen as influential you can start with the wikipedia article. If you want to try again to read it you can try to read it with a guide of some kind, there are multiple, I used this one https://www.ulyssesguide.com/1-telemachus.
No question. It's completely against my being to consider something as good if it can't be enjoyed without a guide. I hated the tendency in computer science to hide simple definitions behind jargon. I'm okay with stuff having hidden meaning, with texts being interpretable, I'm not okay with it just being gibberish when not studying it in closest detail.
I'm aware that some think this book is influential, I'm not clear on how widespread that belief is. Also, whether regular readers really like it. And no, Wikipedia does not clear that up.
Of course it's relevant to how it's seen today. French culture nurtured the author, a French publisher published it, and France didn't ban it while other countries did. This is all evidence that the book was well-liked in France when it was published, and there's no reason to think that would change over time.
If anything, it's surprising that English-speaking countries like it so much.
I disagree, those aren't relevant factors. Just based on those facts it's possible there was one sponsor in France who published the book and then it bombed, never to be read by a significant amount of the public. That it wasn't banned is normal in a free society, but also says nothing about its popularity.
When I don't know, I ask and don't judge (and lacking omniscience, I don't judge anyway).