I've seen concerns that this example makes dragons MORE complicated to deal with; if anything, it sounds LESS complicated to deal with. Anyone who has really run a dragon to its maximum effectivess (with spells, special abilities, and all) knows what I'm talking about. Dragons often have abilities that aren't even figured into their stat blocks, and if they were done so, they would be far more effective. Y'know that stoneskin, energy resistance, barkskin, etc. That was in the stat block? It just gave that 3rd edition dragon an extra effective 200 hit points and 5 more points of AC, which would have changed the outcome of the whole battle. Ever run a Solar in an epic D&D combat? Those guys should probably go up about 4 or 5 CR points if all their defenses are in place!
Even if the dragon got FIVE extra actions per turn, it's still easier than having to plot out what spells they have, what happens when the Wizard dispels them, etc. All this stuff comes directly from a Dave Noonan design article from last year, where he talks about making a CR 20 red dragon for the dungeon delve at Gencon, and realizing that the stat blocks were just too "busy" for the DMs to easily use.