It's highly imprecise, but not impossible. The alerts are already "this is over some threshold of ground acceleration", so there's an inherent severity estimate in the alert going out at all.
But expected intensity information isn't included because:
1) it's still a very imprecise estimate at that time,
2) actual intensity of ground motion (what you care about) will vary dramatically by location, and
3) people don't deal well with that kind of information in an alert that is really meant to be "hey, take cover".
When I was working in SF (Near Montgomery BART), there was an earthquake, but I was at the dentist at the time. The dentist was nearby on a hill near Union Square. The earthquake was not felt at all there, but it was apparently rather strong at the office down the hill.
But expected intensity information isn't included because: 1) it's still a very imprecise estimate at that time, 2) actual intensity of ground motion (what you care about) will vary dramatically by location, and 3) people don't deal well with that kind of information in an alert that is really meant to be "hey, take cover".