There's nothing special about it. Same as a gen 1 sbc.
I disagree.
All aluminum lightweight engine from factory (at not a great cost)
Factory 55mm hollow cam core (lightweight core & lobes that make HP)
Lightweight & stout valvetrain, can spin to 8k as is from factory
OEM heads that flow a lot of air, when cnc'd even more so
Factory cross bolted & skirted 6 bolt mains block, very rigid
Gaskets that are simple to install, and all aluminum covers/oil pan etc
Factory+aftermarket composite plastic intakes that don't heat soak and rob a heap of HP on the street, compared to a lot of old school engines, especially the ones with coolant running through the intake
The OEM intake design gives a heap of low/mid range torque which gets a car moving, makes the LS behave like a bigger CI engine
There are a lot of advantages of it that make it appealing to hot rodders. It's not a "fad", and people just blindly copied. In most cases they have given the user a very good experience. In the very early days of the LS release, 4th gens and vettes were deep in the 11's just with bolt-ons. My own heavy 3700lb Holden/HSV sedan was in the high 11's n/a with just a little 224/224 cam+ bolt ons, back in 2003. And the LS's popularity just grew massive from there.