I've been a member of their heigh-committee for some years, and the question about counting spires would pop up every once in a while, usually ending in leaving everything as is. The reason why they won't change their architectural spire rule is that it's a fairly clear rule what is to be counted or not, and as such minimizes the grey area, but also because the rule has been in place for some decades. By this rule, they counted the Petronas Tower spires as height, while the Sears Tower antennas in Chicago were not, and by doing so declared the first one as the new tallest, even though by mass the Sears Tower appears higher at the top. When changing the height criteria drastically, some of the famous heights, which have pretty much been set in stone, might go out of whack, changing your own history while at it.
However, the problem is that in this day and age, a lot of tall buildings have some kind of wacky something sticking up, and that the current rule produces a number of questionable comparisons, some posted above (especially in post #4). There are a number of cases in which the spire really is an integrated part of the whole architecture and as such don't a clear point which could be considered as a roof. Chrysler Building and Burj Khalifa are good examples of that. But in many, many other cases, the "spire" is nothing more then a stick on top of a roof, even if it is a non functional one. Trump Chicago is a classic example of that. Actually it's possible buying into some kind of "tallest" title rather cheaply the way the rules are interpreted. A number of one on one votes here have shown that there is no popular support for counting these as part of the height, and it is my opinion as well that these should not be counted. By the way, post starter's question has been raised and answered
here.
What that height committee really should to is to draft a set of
qualitative benchmarks instead of
function-based rules, and judge the questionable cases on an individual basis and decide whether whatever sticks out ought be counted as height or not. Until then I don't take some of these vanity heights too serious.