The main reason is the materials used.
Basically, on all bikes with bent forks the bent forks are made of steel. Steel has been mostly replaced by carbon and aluminium.
While steel is heavier, it is not prone to fatigue when bending within its fatigue limit, making it possible to use thinner tubes with more flex and allowing the bend in the fork to work like a basic shock absorber.
Aluminium has no fatigue limit, thus it needs to be stiff enough or it will eventually break, making it not suitable for comfortable flexing forks. A big curved bend puts more stress on the material than a small sharp bend at the crown.
Carbon has properties which are very different to metals. Carbon parts are not just defined by the shape of the object, but also by the layup of carbon fibers, making it possible to get shock absorbing characteristics without needing a bend to work as spring, just by engineering the right layup of fibers.
That's the why many aluminium bikes use carbon forks.
There are other big reasons why bent forks are less common on modern bikes. You could say, why use an expensive carbon fork on your aluminium bike, if a cheap steel fork would be as comfortable?
A thin tubed round bend steel fork just doesn't look right on a thick edgy carbon or aluminium frame. Also thin steel tubes aren't as aerodynamic as the optimized shapes you can make with carbon or hydroformed aluminium.