Having loosely followed this on the mainstream media, I had no idea the crash was self-inflicted and under the influence, they've been very discreet.
George Michael - another latterly troubled soul it seems - had a crash incident (Snappy Snaps) and another time threw himself out of a car at high speed. No one hurt - not even him - so he is now remembered fondly. The circumstances of those incidents remain under wraps, it seems.
If this were a suicide attempt by Heche, well, nobody has to sympathise if they don't want to, but people who throw themselves from buildings run the risk of falling on someone and killing them. I doubt she really thought that hitting a wall at high speed would possibly kill someone else - she should have, though.
Got to say, for someone meant to be troubled, the imdb lists a phenomenal amount of work, with lots of movies and series currently in post-production.