As a long-recharge, late-earned power, Total Focus is meant to be spectacular. It's a Tier 9 (top level) power for Energy Melee, a powerset common to Tankers, Stalkers and Brutes (for whom it's available at Tier 7). It also comes in at Tier 9 in the Blaster secondary Energy Manipulation, in which capacity it's an especially popular choice, way ahead of other Blaster secondaries, and at Tier 7 in the Dominator set, Energy Assault. Once these changes go live, Total Focus won't be able to stun a boss on its own. Players will now have to stack Disorient effects from separate powers to achieve that effect.
Much of the player reaction so far has not been positive, though some have welcomed the change. We're not entirely surprised to see it happen. There have been calls for something to be done about Total Focus for a long, long time now. Energy Melee is a disproportionately popular set in PvP, and the humongous stuns are a big part of that.
Lest we sound too negative, there's some measure of balance involved. Martial Arts has seen some more love, on top of the animation speed increases: 'All versions of Martial Arts Eagle's Claw chance to Disorient a target increased from 75% per attack to 100% per attack', and 'All versions of Martial Arts Storm Kick now have a 5% greater chance to cause a Critical Hit in all cases.' It looks like the developers are pushing hard for greater diversity in player choices, when it comes to melee sets.