History shows that in general you front run to set records but race to win medals. Mostly front running is suicide in major championships. Check out Rob Clarke's career for instance, also note Coe & Ovett's tactics in major races. Regarding the effect of leading the pack the concensus is that in middle distance running the advantage of drafting the lead runner is worth about 1sec/lap. At top mile pace you're probably looking at about 1.5sec/lap (see Noakes, "the lore of running".
Plain and simple: don't lead unless you're going to do something with the lead, meaning speed the race up, slow the race down, or throw in surges.
If you're just going to go up there and set the pace that the rest of the field wants, you're nothing more than a rabbit.
Perfect example: Steve Holman at '98 or '99 Indoor USATF's against McMullen. Led every step of the first 1200 at a pace that McMullen could handle. McMullen sat behind him, nice and relaxed, waiting for his chance to pounce. With a lap to go, he took off, leaving Holman swimming behind him.
To quote my college coach, "If you don't know where you're going, don't f---ing lead!"
Don't blame Holman, it was Gags that came up with that brilliant strategy.
How many people have you ever seen in an American Championship meet take it from the gun and hold on to run a world class time? The last person I can think of is Joe Falcon when he ran 3:36 in 1990 at Cerritos College. If you are in cahoots with USTAF to plan for a rabbit then that is great. Otherwise, the last guy to have the lead.....WINS. Reality bites. But patient, smart and confident milers win.