Is it really worth the tradeoffs of having significantly smaller storage space, reduced screen size, and clicking through way more often, just to not have to move your eyes as much horizontally?

For me seems to be. I keep it in my front shirt pocket, pull it out to read all the time. I've gone through 8 books on it so far this year. That's 7 more books than I read on my Kobo by this time last year given how convenient it is to take it everywhere. Granted I'm usually a paper book reader so my Kobo was always just a travel device, but the Xteink makes it so easy to squeeze reading in everywhere.

The biggest benefit for me is the size of the device. I always have it on me, so I rather read than doomscroll

Just wait until you get older and need to increase the font size. Now you're down to 2 words/line and you get carpal tunnel or De Quervain's from the constant clicking to page. I'm only half kidding.