I mean yes, it is somewhat important?
I'm working on a fantasy universe but that doesn't mean you get away with everything. Of course you can't be an expert on all things in the world but at least trying to be well-informed really doesn't hurt, especially when it comes to major elements, things your characters are supposed to be competent in, or use/experience on a regular basis. (I will need to do a lot of research on traditional Chinese and 12th century Arab medicine because that's basically the technological standart my world has. I won't be super accurate either but having a broad idea of the fields, process of treatment etc. just helps not looking super stupid or like I'm completely missing the philosophy behind it. Then more intense research on the details I need to actually show.)
We learn a lot of half-truths through entertainment, and without doing research ourselves, it easily becomes Chinese Whispers, which ... isn't really good either? Sometimes it is exaggerated or even deliberately misinformed in a way that it does more harm than good just for a more dramatic look, but maybe think about why it has to be super dramatic in first place, or if you can't achieve more drama with other tools than throwing accuracy under the bus. Not to forget that some topics in media might even have been censored to fit a specific status quo (I'm not targeting any specific movement/organisations etc, it's just something you also should be aware of.)
And a lot of that knowledge is actually recycleable! Whether it be to file the info away for future stories or just so you have something to contribute to small-talk, it just broadens your horizon and might even become a great contribution to your creativity (because let's be real, how much medieval Europe fantasy is there just because people are just too lazy to explore other options through research. By now it just feels kind of uncreative and very limiting.)
Doing research imo helps you to also see the connections in the bigger picture and dissect processes, correlations etc more easily, which is a quality that helps you even outside of any creative endevours. And researching gets easier with practice!
I know that I sound very idealistic like that and I mean research can be scary, especially when you get deeper into a topic, then realise some correlations to other parts of your creation and then technically would need to change that part entirely. But that's just how it is. I don't think it's necessarily laziness that makes us not wanting to do research, though, I think it has more to do with being scared of the black on white proof that your previous assumptions were "wrong" (generally speaking.)
Can you over-do it? Of course you can get lost in research, but I don't think that this is a super bad thing either.
I personally believe that only because everyone else is doing/getting away with it, it doesn't mean we should do that, too. If you know you can do better, try to be better. It might even make your work stand out much more than it does without proper researching. (btw trying and failing is already better than being too scared to even look in the right direction. again, practice makes perfect.)
ok that was an unexpected rant