I completely get the high expectations. This comes with 26:17 for the 10k - when you can run 4:13 a mile for 10k it is understandable why people expect 4:40 a mile in the marathon, with a swift finish to boot. We can argue into the night as to when Bekele's 10k record will be broken; it along with Daniel Komen's 3k/two mile, seem very, very daunting.
The marathon is a different beast than 10k on the track, and typically takes a lot of preparation, both in terms of volume of work and duration of training. Given his success on the track (and in world XC, also phenomenal), it may be difficult to get Bekele into the mindset and habits of Kipchoge, who has perfected the marathon like no other. This doesn't make Bekele a failure.
I actually find Hermen's blunt comments understandable - after all - we are talking about a very narrow slice of talent here - people with incredibly unique attributes.