The best feature of HERE, that Google still doesn't have? Telling you where to turn like a human would. Instead of "turn right at 7 Mile Road" (street signs are often difficult to see, or sometimes non-existent), it would say "turn right at the McDonalds". McDonalds is very easy to see.
And like other have said, back then LTE service wasn't as robust as it is today. Having offline maps wherever I went was important. Bear in mind, I haven't used HERE since the Nexus 4 came out.
Why aren't you using it today?
It'll be more difficult to hire and train a completely new team of people, and then hope they're a competent team. It's easier to just get the developers who are already experienced with their tools.
This'll be difference if the skill set was somewhat popular, but it'll be difficult to find people who really are good at OSM and the surrounding software + who are willing to work for Intel.
The only contender is Osm with is already better than Google in some country and evolving fast.
Some good example is the maps.me application on Android and iOS which is an open source offline map application with everything needed. And you can even contribute to osm from the app.
So why do they buy something which is worse than a free one?
Maybe I'm just missing something.