Many modern laptops still do this though. Dell XPS had some LEDs on the side and a button on the case that when pressed would light up the LEDs as a percentage indicator of battery charge, and my 2 year old Lenovo has this feature built into the motherboard EC controller and Bios that when I press any key on the keyboard when the laptop is OFF, it wakes the laptop's own display to show battery percentage. Modern laptops have many neat features.
Some large OEMs with the resources to do the design effort could use a large passive heatsink on even surprisingly late processor (i. e. Pentium 4) because they could make a holistic design with shrouds and baffles and know you were getting just enough airflow from a case fan elsewhere to keep the CPU within spec.
Early ATX designs, in fact, were often based on "the PSU has its fan placed so that it will draw air over the CPU heatsink and out the back"
Enthusiasts, obviously, went for brute force designs.
I do miss some of the sounds that let you know machines were doing something - but we also had indication lights, too - mostly gone now, for disk drives. Heck my first laptop had a second LCD to show battery level without the machine even being on.