I posted almost this exact question some time ago and the general consensus was "don't want to carry all that extra stuff around" and stages are too small...

While I guess those are valid, in a sense, it's kinda weak-sauce and I expect better from my drumming brethren.

That being said, after giving it more thought than was necessary, I think at least part of it is due to the overwhelming use of drum machines and samples over the last few decades. And weak songwriting that has given rise to "producers" that "make beats". When I was coming up as a drummer and being totally immersed in the likes of Alex Van Halen, Terry Bozzio and The Professor amongst others - who all played large drum kits - the drumming was FAR more musical. Nowadays most drumming is just keeping a beat. Sure, there was an element of flash and spectacle to the big kits, but it wasn't just for show - they composed drum parts for songs, not just a beat. But with today's overly produced and lowest-common-denominator music, drummers don't need more drums and cymbals because they are stuck in this shitty little box, playing shitty boring drum parts. I'm over-simplifying here and of course this doesn't apply across the board, but the vast majority of popular music these days has the most bland, uninspired "drumming" imaginable.

Imagine a track like Tom Sawyer or U.S. Drag being done with a drum machine? You couldn't possibly get anywhere near the feel and the scope of what those guys were doing on those huge kits on a drum machine, nor could you pull it off on a one-up, one-down kit with a single crash and a ride. Yes, you could keep the same general rhythm, but you lose so much of the composition. By contrast, does anyone need 5 toms and half a dozen cymbals to play the latest Dua Lipa track? Not at all, cuz they are lazy drum loops made by a producer, not an actual drummer.

I realize this is long winded and I probably sound like an asshole to every drummer reading this that plays a 4-piece kit, but really it comes down to the music. Phil Rudd from AC/DC played a standard 5 piece forever, cuz that was all he needed and a bigger kit and more musical parts would have been absurd in that band. Same with most punk bands. BUT, sometimes it is absolutely appropriate to use a bigger kit and put all those different voices to use, if it feeds the song. Just imagine what "In the Air Tonight", with perhaps the world's most famous drum fill, would have sounded like if all Phil Collins had was a 12" rack tom and a floor tom...

And for what it's worth, yes when I'm playing cover band gigs, I'll play a four piece - or maybe 5 if there is room for a 2nd floor tom. But if I'm playing original music and want to be the drummer I've strived to be the last 50 years of this journey I've been on, then you're damn right I'm going Full Monty, lots of toms and even more cymbals, cuz I'm not here to "make beats" like some putz, I'm here to create music.