I've noticed a trend over the past several years of people in the brewing community hating on crystal malts. Although they are probably the most widely used specialty grain and feature in the overwhelming majority of "craft" beers, it seems like the overuse of crystal malt in lower-quality IPAs (especially like those produced by second rate breweries from ~2005-2015) has led brewers to believe that crystal malt, even in small quantities somehow "clashes with" or "dampens" hop flavor and aroma. While this somewhat makes sense in the context of the ever-evolving IPA style, and there is certainly merit to the concept of simplifying malt character in a beer that is predominantly a hop showcase, I have noticed the trend extend beyond IPA (indeed beyond hop-forward styles generally).
I recently encountered a discussion on another forum where the OP discussed missing the hoppy red ales that were popular about a decade ago, like Green Flash Hop Head Red and AleSmith Evil Dead Red. He sought to recreate this style, but opted not to use any crystal malt, despite knowing that various types of caramel malts contributed prominently to the character of every commercial example he cited. When I inquired, he stated that he replaced crystal malt with heaps of melanoidin malt and chocolate malt since "we’ve learned more about that interaction [between hops and crystal malt]," indicating that crystal malt inherently interfered with hop flavor in a way that melanoidin-rich malts and roasted malts do not.
Not long ago, I took part in a group brew where we customized an Imperial Stout recipe. Here there was a push to exclude any crystal malt, as well.
I think there are three main things that crystal malt bring to a beer: flavor, body, and residual "sweetness." I put "sweetness" in quotes because while residual sugar/starch is what I mean and that does not necessarily come across as "sweet" on the palate in every single scenario. Body and residual sweetness are related because unfermentable sugars are going to provide both. I understand fully the desire to limit sweetness and body in certain styles. That's why I use zero to very little crystal malt in a Festbier, for example (I can take or leave about 2% carahell or carafoam). And perhaps in an IPA, maximizing dryness might be desired in a west coast example and a New England version may get sufficient body from the adjuncts and sweetness from the use of a less attentuative yeast strain. Neither of these perfectly good reasons to omit crystal malts from an IPA (or several other styles) really apply to a hoppy red ale or an Imperial stout, and they weren't the reason given by the different brewers who objected to the crystal malt.
But the real issue that a lot of my fellow brewers are having with Crystal malt is its flavor. In my mind, the flavor ranges from a subtle honey nut cheerios sweetness in something like a CaraHell to a dried fig and date-like rich fruitiness in something like a Special B. Typical C-60 provides the most "classic" crystal malt flavor, I think -- a syrupy quality that I associate with a varie5ty of older craft beers and, at worst, insipid amber ales. But I also see C-60 in smaller quantities in some of the all-time best IPAs, even. I suppose I just don't understand what is so widely objectionable about this family of malts that makes it "off limits" for certain brewers or "off limits" to beers with notable hop aroma. I assume it's that an IPA with ~10% C-60 (common for a time) is going to be fairly sweet and heavy. And an under-hopped red ale with ~10% C-60 and another 2-3% C-120 or C-80 is going to be an unbalanced malt bomb. But while a beer with 10% Melanoidin malt and 4% pale chocolate might not have the same "caramel" taste, it can have the same finishing gravity by adjusting mash temperature or yeast choice, so it doesn't strike me as fundamentally more "hop-friendly" unless you judge melanoidin and roast to be more of a hop-friendly (or "hoplimentary") flavor than the flavor imparted by caramel malt. Of course taste is subjective and people are free to not like a certain flavor combination that I like, but I wonder if it is now more of a "homebrew myth" that crystal malt is a beer ruiner (the way Ringwood was a beer ruiner back in 2006).
In any case, I like crystal malts and use them in many styles, but omit them from others. I tend to like about 4% carahell in an IPA and I always use a fair amount of crystal in a red/amber ale, brown ale, porter or bitter. I don't understand the hate, but then I also never understood the love people had of certain styles (looking at you NEIPA and "Gose").
I'd love to hear others' thoughts about the C-hate, especially if there is something I am missing. It always struck me as odd that so many people don't find melanoidin-rich flavors odd in a hoppy beer (hoppy Oktoberfest is not what I want in an IPA, personally).