Honestly, this is just sad to see. I was one of the early adopters of the manga, (and to this day I still remember how I discovered the manga back when the first 10 chapters were scanlated). I hate the "it's popular, so now it sucks" mentality. The criticism towards MHA's current arc is understandable, but it feels like the criticisms are overblown. Personally, I think it's because most of the critique stems from looking at the series in a short-term point of view instead of the bigger picture.
The spotlight on the other classes imo, is setting the ground for future events down the road, and I think it's going to contribute to the plot in a meaningful way. The pacing could be better of course, but overall, it doesn't affect my views on the manga's overall plot in the slightest. But most of all, I think some people are taking Horikoshi for granted. Especially when I've seen worse. That's why I'm grateful for what we have in MHA, warts and all, when I think there could've been worse alternatives Horikoshi could've taken.
As for BC, I get where the hype is coming from now. I've been an on & off reader, but I've got the gist of the current arc, and I can see why, in the past year, it would look like BC has an edge over MHA. BC is a good manga, but if I want to wholeheartedly devote myself to a series, I want that something "special" that I've always experienced in my past manga viewing experience.