I find it semi amusing that despite the general agreement that there are different play styles and thus different desires when it comes to stat blocks, it seems hard for some to admit that others might genuinely enjoy slighty longer, more detailed stat blocks.
If you like short stat blocks I'm happy for you. I on the other hand, enjoy being prepared for some contingencies. It doesn't matter how likely or unlikely you think any given piece of information is going to be used, to the person who uses it - it was useful.
Heh, I love how you put it at "slightly" longer. Prepared for "some" contingencies. Hrm, 3e stat blocks aren't "slightly" longer. They can take pages, and yes, that's pages plural. You gave an example of something that had about as much likelihood of occurring as the PC's spontaneously combusting for no reason, but that's apparently only a minor contingency.
Take this as an experiment. Look at the last ten encounters you ran (not necessarily combat - just encounters with stuff outside of traps or hazards) in your D&D game. Of those ten encounters, tally the total number of NPC's featured.
Now, how many of those NPC's appeared in a second encounter?
I'm willing to bet that the overwhelming majority of NPC's featured in exactly one encounter - either combat or non-combat or possibly a combination of both. So, considering that the NPC will feature in the game for a grand total of about an hour, probably far less than 1% of the total time of the campaign, why does that NPC need a fully detailed stat block?
I mean, for much of D&D's history, OD&D, AD&D, 2e D&D and now 4e, monster stat blocks could be reduced to a single typed line. And, yet, somehow, we managed to muddle through for about twenty years or so of gaming.
What were we doing differently?