There's a point to be made for the quality of all these recent adaptations in different media diluting the Berserk brand.
Oh, for sure, but that's a given when it comes to the expansion of any brand, and I think the expansion is the point, and there's some logical reasons for that, not all of which are detrimental. To be continued...
In comparison, the DC game or the 97 anime are masterworks (mainly because of Miura's involvement).
In my estimation it's actually incredible how bad Berserk-related media is today; it's so much bad luck and bad timing it's like a curse! I mean, the '97 anime is like some classic of the form compared to this current shit, and the movies are somehow relatively tolerable by comparison (at least they had some animation =)! Even Berserk video games suck dick now. It's disheartening, especially for a fan that's looked jealously upon lesser, yet more celebrated, series and thought, "Why not Berserk? It should be so great!" I guess the moral is be careful what you wish for, and be grateful for and satisfied with the manga being great, which is all we had to lose here in the first place...
So far the manga hasn't dipped in quality, but the longer breaks make it easy to assume that Miura is in the Berserk game for life. I don't know how much control he has over the property outside of the manga, but it seems that he's just saying yes to every other project and cashing in. The increased popularity of the series attracted more garbage/cheap third-party content, and even though i don't consume it, it's not pleasant to witness. Are we becoming more forgiving because we choose to believe that Berserk will never be influenced by all that bears it's name in it's periphery? Miura's involvement on those early adaptations/side stories, kinda show that he had a sort of preciousness towards the Berserk name that doesn't seem to exist nowadays.
First, I actually don't think he's "in it for life," at least not by choice or in a cynical way. But let's consider all you said and put it together: Miura has benefactors, publishers or "investors" to please one way or another, and he's producing "first party" content at a decreased rate while maintaining high quality and ridiculous standards for a long-running serialized comic with a single author and modest staff. He furthermore doesn't have time for every side project, let alone this many, as when Berserk was smaller and there was, like, two. So, even without truly knowing the dynamics at play, it's possible, even probable, all this Berserksploitation crap that's more popular than ever is basically subsidizing the continuation of the manga at such a quality. I don't like the cesspool surrounding Berserk any more than you do, but if it's helping keep it afloat in its current form I'll take that deal rather than have him compromise what's important. Anyway, I'm not saying Miura is some victim here or Berserk would hit the skids without this stuff, but I think it makes sense, makes things better/easier for him to do
his work on his terms, and he doesn't have the time to play arbiter to everything or the inclination to be some raging creative dickhead about it.
I think this is easier to compartmentalize for a child of Star Wars (it always comes back to STAAAR WAAARS

). The Manga is to the Original Trilogy what everything else is to the EU, and this latest animation is like The Prequels. Yes, quite unpleasant to witness, even if one knows not to consume it, but unlike that scenario at least there's fresh and continual payoff to reward and invigorate purists that have the good taste to stick with the manga and ignore the noise surrounding it. Now that's a far rarer and pleasant thing to witness.