This 5% overall raid buff is just like nerfing the boss after it has been out for awhile, mostly after a week or two. In ICC's case, the raid is now out for about 3+ months (3 weeks since the heroic mode was unlocked), and boss that has been nerfed was only deathwhisperer. And nerfing bosses have been around since when, last 5 years or so?
The only thing that's making me laugh is, The Lich King, THE BIG DOG, was never defeated on hc mode in either 10 or 25 man before the raid buff (in other word, before he was nerfed), making him the toughest boss ever. Suck's for people who cried for the past 1.5 years about wotlk being faceroll, when wotlk provided the top 2, most difficult bosses the game has ever seen, THE LICH KING and YOGG-SARON (without keepers). Not to mention some awesome other bosses aswell.
This is a sweet, sweet victory and it is I, who feeds on your tears now. farewell