[giantrobot]

That's one more thing to go wrong. In a LES scenario something(s) has gone wrong in an unrecoverable way. Very few systems can be relied upon to exist let alone work correctly. A LES on a crewed capsule is supposed to be able to pull itself from the vehicle all under its own power. It can't assume explosive fasteners on the fairing are functional or actual all function correctly.

You don't want the LES to activate, seem to be working correctly, and then blast the crew into a fairing panel that did not fully separate. The crew doesn't have time to roll down the window and kick it loose.