Ever since Wrath of the Lich King, Blizzard has toyed around with its concept of "heroic" raiding. What first started out as a mere distinction between 10- and 25-player boss fights eventually became a difference in difficulty that was available in both raid sizes. It iterated further from Ulduar's various "hard mode" triggers to a simple UI element that toggled the "Grand" in and out of Trial of the Crusader. In ICC, Blizzard seemed to finally settle on how it wanted things to work.
Heroic mode is still relegated to a UI element, but it can at least be changed on a boss-by-boss basis, which puts it a step above the Argent Tournament's four raid lockouts. I must say, though, I do miss the creative methods of triggering hard modes in Ulduar. Leaving up the towers before Flame Leviathan or killing XT's heart to throw him into a new phase were clever and engaging ways to change up fights.
These days, there's no fun to be had in turning these modes on -- you just a flip a switch and sit through a loading screen. I wish it were possible to bring back a more meaningful method of triggering heroic modes. If you ask me, it would be great if you used a machine to "wake up" the additional drakes for heroic Halfus, for example. The downside to this type of toggle, of course, is that there is much more room for player confusion about how to activate each hard mode. I think it's a fair trade-off, though.
How about you? Do you pine for Ulduar's version of hard modes, or do you prefer to set it and forget it in the UI? Is there anything else you would change about heroic modes?