Yeah, Plex also only provides one minute previews on mobile, unless you subscribe, or pay a premium for each device you own (I have an iPhone, an iPad, and an Android phone) to unlock full functionality on each. Many services provide full functionality on desktop but not on mobile (like Spotify), as most people use mobile devices primarily these days. Smart! That was the main reason I wanted to get a Plex Pass for a long time, but used to use the web app interface in Chrome on mobile, like on desktop, instead of the native app (not a good experience, but it worked and I didn’t have to pay anything)… Used to feel really bad, I really love Plex and it’s one of the very few things I’ve used in life that just scream quality and satisfaction, something that really surprised me with everything it can do, and far exceeded all initial expectations. Beautiful UI, all my media in one place, with lovely posters, artworks and more, all effortless.
But they provided all the essential features for free, and I had the workaround for mobile app limitations (also, kinda really don’t like the mobile app), and the other premium features are nice, but I didn’t really need them either. So I held out on getting Plex Pass like you. But now they have the TIDAL HiFi + Plex Pass bundle which is perfect for me, and arrived at the perfect time too, gonna purchase high-end headphones soon, so wanted to switch to TIDAL. Now I get both at once. Life is sweet!
Also, really enjoying the extra features that come with Plex Pass, and can finally use the native apps on mobile (and they said they’re gonna update the apps with new UI like on desktop, so that’s great… again, perfect timing), and it’s nice to have no limitations, extra fun and useful features (like dashboard, cinema trailers), although I still feel like I’m getting more for free now than ever before, because the TIDAL bundle is the exact same price as of TIDAL alone, and now I’m getting all Plex Pass features with it. So essentially I’m just paying for TIDAL. But whatever, really enjoying everything! And you - yes YOU - should start paying as well, you cheap “insert censored swear word here” 
Seriously though, they deserve it… Great service, and if you use mobile devices, it’s gonna be really worth it. And they listen to the community as well (as they recently demonstrated). It’s not something I really demand, as there’s a lot of people using these things, and everyone has their own needs and likings - some people can’t do without HTPC, some don’t care (like me), and others don’t even know what HTPC is… And it’s really difficult to listen to and cater to everyone. I like it better when developers do what they feel is best for the future, and stop trying to please everyone, trying to add everything people ask for, making changes all the time. Like how annoying is it that mobile apps keep getting insignificant updates every few days? All this only keeps making every software/app more and more complicated and buggy and messy, and they never manage to please everyone.