It's not a flaw, it's a feature?
Heh. Kidding aside, I'm sorry, but I don't agree. Entirely random elements are not a great way of introducing important characters. Sure, there is a chance that the evil priest will be in the tavern. 10%. But, there is a much greater chance (90%) that he won't be. In other words, a major source for an interesting line in the module is relagated to a single die roll.
I find it strange that people would say that random, rare elements make for good game design. It doesn't matter how fantastic the idea is, if it never sees the light of day, it's a wash. Who cares that there is an evil priest in the Keep if the party never meets him?
Again, it comes down to how you define good design. To me, elements which are so rare as to hardly be seen, are not an example of good design. To meet the priest, by the module, you have to go to the tavern. Never mind that there are two places to eat and meet people, and the party is likely staying at the other one since the tavern doesn't have rooms for rent. So, right off the bat, there is less incentive for the party to actually be here. Even if they do go here, there's only a 1 in 10 chance that they can meet the priest. The other nine times, they don't.
My point, if you swim back upthread a bit, was that the odds of actually meeting the priest were slight unless the DM massages the situation. I'm not sure if that's an assumption that can be made in a beginner module.