In short, yes, but let's dive into it together.
Like most mountain bikers, I ride all year round. We ride in the rain, wind, sun, and snow. We ride through dirt, loam, grass, poison ivy, nettles, dog shit, etc. We never stop riding because we love it too much.
To decide if mountain bike pants are worth it, you need to consider style and necessity.
Style is personal, I prefer wearing pants, but that's on me. So style is something only you can decide. However, if you go with pants, don't forget that there is a reason mountain bike pants are not overly baggy, and that is because getting your pants caught in your chainring is no fun at all. Choose well, or get ready for some wild riding.
Now for the necessity, it depends on how and where you ride. I ride a lot in the rain and mud, and I ride on overgrown trails and through high grass. I also ride a lot of bike parks and jumps. So for what I do, I prefer pants. They give me extra protection when I crash, protection from the weather and mud (a good pair of waterproof pants will keep me warmer and cleaner in the winter), and it saves me from cuts and ticks in the summer. Belgium is not the hottest country on earth, so I ride in pants most of the year.
If you ride in a hotter region, some lightweight pants with a lot of ventilation are available on the market, and they might be a good fit. However, nothing beats a good pair of shorts when it gets too hot.
So are mountain bike pants worth it? Yes, if you ride all year round or prefer the style.
There are many options available out there, so be sure to buy from a brand that shares your values.