People don't like Gleba because it forces you to play differently and not just re-do the optimized builds over again.
Hey man thems fighting words. I like doing different builds but hate feeling rushed with a nonstop ticking clock on an otherwise chill building game.
Gleba introduces things like spoilage.
That makes production more interesting: On other planets (or Factorio 1.x), a belt can generally get backed up and that's no big deal. In fact, it's a useful game mechanic: Decreased demand is followed up (eventually) by decreased production. With this feedback, things tend to balance themselves well-enough that the game doesn't stall.
On Gleba, though? A backed up belt means more spoilage, which I liken to trash. That trash needs to be dealt with somehow -- whether burned or converted to nutrients or whatever, it's a problem that accumulates unless it is dealt with.
So it ultimately becomes necessary to find new (for the player) ways to limit production so that there's less trash and fresher ingredients for the stuff made on Gleba. That's is a new mechanic that I'm sure that some people find fun, but some folks just don't seem to like very much at all.
I don't mind playing on Gleba, per se, but those parts are annoying to me.
So I'm pretty lazy about it: My waste management system is centered around purple chests and a continuous flurry of bots. My production limits sometimes don't exist. I make up for this lazy play style with artillery, which Vulcanus is profoundly excellent at producing.
(Vulcanus, in turn, is often oil-starved so exporting with rockets might sound expensive. But I have tankers that bring in oil from the bottomless seas of Fulgora, which themselves become efficient with a small amount of productivity research. Dealing with the thousands of empty barrels that this requires has its own challenges, but that's just Factorio things and I enjoy working on this part more than I do finding tidy ways to sort garbage on Gleba.)