It's like reaction channels.
The problem isn't reaction channels as a whole, it's what the majority of them look like. There are some great channels like h3h3productions that I'd classify as a reaction channel, but they take time making thought out videos, which are their own content, and really entertaining. The much larger and uglier flip side of the coin is these reaction channels that just have a guy sitting there watching an entire episode of a show, barely even cracking a smile the whole time.
Prank channels are similar. There are some really great prank channels. Just last night I was binge watching some funny pranks on Infrabren and JStuStudios' channels. The problem isn't with the good channels, but with a lot of the popular ones that are shady. Firstly, fake pranks, a lot of the really popular prank YouTubers hire actors for their pranks, simply because if you're a prank channel, realistically speaking you're going to be able to make more money if you get fake reactions and the like. Secondly, the whole sub-section of pranks that is basically just slightly less NSFW and Youtube-legal p**n. "kissing pranks" and the like where it's basically just a video of the YouTuber making out with paid actresses, which get a ton of popularity despite being obviously fake simply because a lot of horny teens are watching them.
If you can make original and interesting pranks, without faking, using clickbait, or going down the whole weird route that is "kissing pranks", then go for it. I'd love to see some good new quality prank channels on YouTube. The good ones are some of the most entertaining channels I've watched. Just sucks that the amount of rubbish/fake/weird ones tends to outweigh that.