» Mon Dec 16, 2013 11:36 pm
Killing Jarl Laila Law-Giver's dear friend Maven would probably net you a lengthy prison sentence and probably an execution. Meanwhile, Hemming steps up to bat and moves to expand Black-Briar Mead and their control over all of Tamriel. That, or ruthless Sibbi takes control of the syndicate. And you've murdered the livelihood of all the mostly-impoverished meadery workers, so good job.
Dealing with these problems head-on is usually not the best option.
If you killed Mercer, the Guild would probably be in disarray for a while until a new Guild Master was in place. Since no one has any reason to suspect Mercer until Karliah reappears, there's no reason for anyone to peruse his journal (though if his business records held anything, that might lead somewhere) and there's no guarantee anyone would recognize the Skeleton Key. Since the Key hasn't been returned to Nocturnal, her curse is still in effect, and the Guild continues to decline.
Also, trying to display Mercer's journal to the Guild (assuming he even has one) after you've murdered him would probably make them suspect you forged it -- and would they really make the murderer of the previous Guild Master the new one if they knew he killed him...?