I tested ABS during the test patches campaign and allow myself to make some hypothesis from these tests.
ABS saves your tyres, but does not make you much faster (at least LFS implementation of it). The ability to modulate braking force will make you faster.
However most of us use a travel related brake force, very difficult to modulate, or On/Off brake force, impossible to modulate. The implementation of ABS will help us getting safer beginners (no more T1 lockups) so overall more enjoyable races. The more experienced drivers / realism strivers will not use ABS as it is not faster and boring (but gives consistency).
Scawen has implied not so long ago that we may see setup restrictions. If one of the setup restrictions is related to minimum brake force, and mouse driving / kb driving are still supported, then ABS will become a must.
ABS/TC will eventually become server options in my opinion, similar to reset / forced cockpit view.