Apple's acquisition of Fingerworks provided them with the multi-touch technology (and just as important, IP) that they used to build the iPhone. Definitely one of the most important acquisitions in their history.
I have an old Fingerworks trackpad and it works amazingly well even today.
I think there's some survivor bias in your list. I remember Apple acquired a public transit app (Embark, I think) and I'm not sure the fruits of that were ever known. Apple Maps has public transit features but it's a shadow of what that app provided.
I am one of the Embark founders. I'm no longer at Apple.
Our acquisition actually ended up with the spirit of our product living on in a way that I am proud of.
At Embark, we innovated by taking a regionally nuanced and tailored transit App and giving it scale. When Embark operated from 2008 to 2013, there were small bespoke apps and there were larger more generic experiences (like Google) and we filled a void in between.
Apple's approach was quite similar. Like Embark, Apple Maps Transit has a more regionally tailored experience than many bespoke transit Apps out there, but they're also able to bring it to scale. It's now at a scale we never got close to reaching at Embark.
I seem to remember an incredibly nerdy and thoroughly enjoyable article about the arcane details of drawing subway lines. It was written, IIRC, by a startup that had automated the process of optimising these maps, only to have Apple launch their maps – which had brute-forced the problem by doing it manually.
You're cherry-picking the biggest, most visible of Apple's acquisitions. You should be comparing Workflow to the dozens upon dozens of Workflow-sized acquisitions they have made.
I can't recall many of them off the top of my head anymore, because they're gone and lost to memory.
NeXT -> OS X
LaLa -> iTunes Match
Siri -> Siri
My guess is that Apple saw a useful product that should be a part of the core of iOS.