Personally I appreciate getting to know here whenever something got updated on mangaplus, saves me the trouble of going there to check..
Generating traffic over there also helps the authors and let them know how liked their series are among other things.
While they certainly could improve their interface for one, it's a legal free source connected to the authors in question,
making it real simple for any of you that said you wanted to show support while having no money to buy products.
Last but not least, the more popular they know a manga is, the more likely they are to try release more.
Likewise the opposite holds true too with the axe, another reason to try read your fav series from official sites even if you prefer and will read fantranslations at the side.
Still, really wish they'll improve their interface sometime soon, having no control over resize to window settings for one is rather frustrating.
(Or the fact that long-strip occassionally jumble up the pages and display them in the wrong order, to name another of many annoyances.)