As soon as something becomes routinely doable by a computer, it is no longer considered a sign of intelligence; it's a mere mechanical activity.
Correct. I have observed this thought in myself. I also wondered whether I deceive myself. But this is something else than AI: AI aspires to create "intelligent" machines, which can:
learn, understand, and reason.
Without having been programmed specifically. To follow a certain programmed algorithm, which is simply processed and executed, doesn't count as AI for me. That is then indeed purely mechanical. Input -> specific, given process -> Output.
What we see is that we can program ever more jobs as such a mechanical algorithm, through advances in hardware and software as you describe. Our toolbox increases, gets more powerful, therefore we can build more powerful, more useful machines. We can take a data source like the ID3 tags of songs played in Amarok, and compare that with those from other users, and find matches and differences, and based on that make proposals. 20 years ago, we'd have said that needs a true music lover or an inspired music shop owner, but now we can program it with our bigger toolbox. We can even generalize it to arbitrary data sources (RDF, OWL). Nevertheless, it's still a mechanical process that a human has analyzed, abstracted, broken down, and expressed as mechanical steps using the toolbox. It's the human who thought it out, and the computer just follows a given work pattern.
This is very useful and on a very high level, but it's per se not KI for me, because the computer has neither learned nor understood nor reasoned. Throw corn in from the top, run through mill, get flour out at the bottom. "Routinely" and "mechanical" are the key words in your comment. Sorting letters into a file folder cabinet is a routine that requires no intelligence, even if a human executes it. Inventing sorting was intelligent. But it only needs to be done once. That's what computers are good for, IMHO: Routine. We are striving to let them do ever more, higher-level routine jobs.