For example, it's impossible to watch 4k content on popular streaming services if you use Linux, and even with macOS/Windows you need a specific combination of hardware + OS + browser, if a service even offers it.
So I'd put accessibility and consistency as important parts of UX that torrenting can often miss out on. For the common person who is using Windows/Chrome, macOS/Safari, or a gaming console, those parts can easily be more important.
Of course, these methods start to shine when legitimate methods are even less accessible. For instance, U.S. sports streaming is an absolute mess with multiple networks, regional blackouts, etc., on top of buggy apps, so that you sometimes can't watch a game legally for any price. People have widely picked up illegal streams as an alternative, usually preferring familiar platforms like YouTube if the streams aren't taken down quickly enough.
As far as I’ve seen, they pretty much grow on trees as far as films are concerned. TV shows are a very different story though and outside of hugely popular series are far more inconsistent.
You have to learn how to navigate an ever-dwindling list of trackers and probably a VPN, which is already too tall a hurdle for the overwhelming majority of people. Time is often worth the price of a 4K Roku and a subscription, even though that's still a technically inferior experience at the end of the day.
Piracy has two very hard problems: privacy and moderation. Moderation requires authority; authority requires trust; and trust relies on identification. I think we might be able to resolve this by replacing moderation with curation, but that's going to take a lot of ground-work that I'm too ADHD to do myself.