Apple has taken some heat for the story that they intentionally throttled performance on their older phones. In the rush for those who always seek sinister motives from large companies, this is the rest of the story.
Upgrades tend to use more power as new features are introduced. To conserve the battery power of older phones, Apple reduced the processing speed, assuming a small difference in processing speed would be more tolerable and less noticeable than a battery that drained too quickly. This is hardly the sinister motive or forced obsolescence the conspiracy mongers attribute.
Perhaps they could have been more transparent in their warnings on their upgrades, but their decision was consumer centric, and if anything sought to extend the useful lives of their older products.
Their apology was unnecessary but probably cheaper in an age where the publics prefers demons to legitimate explanations.