I guess its how you look at it:
BC
Levels: 10
Dungeons: 16
Raid Bosses: 51
Wrath
Levels: 10
Dungeons: 16
Raid Bosses: 45
Cata
Levels: 5
Dungeons: 11 (2 of which are old content redone) so 9, add the 3 new ones and total of 12
Raid Bosses: 22
As the numbers show the content is far far behind previous expacs, unless you think the last raid instance will have 23 bosses...