In the present, I agree with you; it is frustrating to wait a whole month to find out what happens next only to get a tiny snippet of information, with most of it flashbacks.
However, once the series is complete, and we have access to the whole story, I think we will appreciate the "filler" a little more, since we won't have a tedious month-long wait to read the rest.
For example, I started reading the manga April of last year. By that time, the Uprising arc was pretty much done. To be honest, I liked the Uprising arc, but I admit it was a little slow at times.
Now, can you imagine if I had to wait a month every time I wanted to read another chapter of that arc? I'd probably get bored of the series after a while.
My point is that having the series as a whole will allow us to appreciate these filler moments more.
I can't wait for that moment.
But in the meantime, still an emotional and impactful chapter