A common, and very flawed, reasoning... especially for this draft.
Over the last year, some teams had to cut back on personnel, which would include scouting. Some didn't have the resources to scout as deeply as they normally do.
Also, some teams make the mistake of drafting on need.
Don't forget to bear in mind that just because he fell so far, doesn't mean he was the consensus 54th best prospect. Some teams that weren't foolish enough to draft for need, had at least one other player rated ahead of Latendresse. For all we know, he could be regarded by Montreal as the third best prospect behind Crosby and Price.
It's draft position, not Latendresse, that's quickly becoming overrated.