Mattk -- I'm not sure it's fair to say that she doesn't have the mental strength for sport. She seemed pretty strong against Serena from 4-2 down and against Aga from 3-0 down after all. Even in this match she was showing signs towards the end of finally turning up, but it was too late and Bartoli served it out phenomenally well.
This was her first Major final. Maybe it got to her so much that she couldn't play. It happens to many people and they end up coming back stronger. Look at Murray after his horrible sequence at the AusOpen and Wimbledon Finals before winning in the US Open, and I'm sure he's not the only one. Many people are uptight at the first chance.
I'm not sure Lisicki's game lends itself well to the sort of reining in you need to do when things aren't going your way. Going for those awesome winning shots is fine when it works, but if you keep missing you need a plan B. That's what Lisicki will need to develop in future if she's to win a Slam. I think she could win Wimbledon some day, grass is her best surface and she'll continue to meet and threaten the big names here, but today the occasion got to her. Next time... who knows?