It was nice of them to deliver such a personal rejection, I mostly just get automated letters or nothing at all. But maybe this was a bit over the top..

Take their feedback and adjust your presentation and resume for future applications to similar jobs.
Drop them a letter thanking them for the frank assessment and advise them you are are making the changes they suggested and you hope they will reconsider you in the future
That type of initiative could get you reconsidered later,if the person they hired doesn't complete the probationary period, or considered for other openings later
Management looks for people that can reflect, learn and adapt

Good luck with your search, you got passed the screening of resumes to the interview stage, so you are on the right track