And now, I shall state the obvious: Mycroft Holmes is cool.
I feel inclined to state that these days because the American television branch of his P.R. seems to be doing an especially weak job of relaying that fact to the citizenry of the U.S. So let's review the facts.
What's the number one reason Mycroft Holmes is cool?
Not the hazy, yet important government job. Not the club of silent men where he recreates. Not his enormous girth and flipper-like hands, so oft-ignored by the media.
Why is Mycroft Holmes cool?
Because he's smarter than Sherlock Holmes.
Here's how it works: Dr. Watson introduces you to this guy named Sherlock Holmes. And Sherlock Holmes is a frickin' genius. Not like an Einstein genius, like a genius who can be Harry Potter amazing with no magic in the world. And just about the time you're going, "Wow, this is like the smartest guy on Earth!" Sherlock Holmes pulls the rug out. How?
By introducing his brother Mycroft, who can do what Sherlock Holmes does, only better. Watson tries to put the thought down to modesty at first, only to have Sherlock basically say, "No lie, he really is better!" And Mycroft doesn't even care to use his better-than-Sherlock skills to be a detective!
How cool is that? Just sitting around his club of silent men, patting his big ol' belly, going, "Yeah, I could help individual people with their problems, but I'm going to do it on a global scale instead." You could actually see the decline of the British empire coming, based upon its eventual overdependence upon a guy who was probably going to die of heart disease not long after the Victorian era was done.
One could probably construct a formula upon the declining rate of Mycroft's coolness based upon his presence in a given story-set. Original Canon had 6.666666666 (etc.) percent Mycroft. If you want to round that down it's 6.67 by the way, so he's not the Revelations Beast . . . besides Revelations didn't happen when the Victorian period was done. It's more interesting to note that if you round it to a single digit, the Sherlockian Canon is a seven percent solution of Mycroft.
Adding more Mycroft seems like a swell idea, but the next thing you know, he's jogging on a treadmill wearing a funny track suit or trying to date Dr. Watson. Lord only knows what a Mycroft who appeared in three or four Basil Rathbone films would have turned out like, given Rathbone's eventual hair styles and Bruce's . . . well, everything.
A little Mycroft goes a long way. He can still be an interesting fellow with more usage, though, if you stick with what brought him to the party: He's the one guy who is smarter than Sherlock, and Sherlock knows it.
Because that is what makes Mycroft Holmes cool. Now and evermore.