I disagree. Even if they gave them a high quality data set, that set is going to be obsolete within a year (let's say). Now Apple can either choose to keep obsolete data (which will definitely impact customers) or buy updated data from TomTom.
TomTom's problem is that their devices only communicate one direction. A partnership with Apple could have allowed TomTom to collect realtime data directly in the same way as their major competitors.
In the next twelve months, Apple will probably have collected more useful data than TomTom in many respects. That doesn't mean they will be successful in using it to their advantage, but it does mean that there is little reason for Apple to purchase a new dataset.
Maybe my creativity is limited but I just don't see how Apple being able to collect data would help with getting updated maps. I think it could help with their directions since they know the most commonly taken routes and could actually even time people's routes to find which are truly the quickest, but I don't know how it would help with updating maps from road changes and the like.
I have fallen victim to this. I bought a new used car (it's new to me but a 2007 model) that has built in navigation. Between the date of manufacture of the nav disk and current date, an interstate was added/modified near me. Now everytime I go by that area my GPS says I'm in the middle of a field. In reality, I can't see a customer filing a ticket with Apple to get that road in the GPS system. Even if they do, Apple would most likely need coordinates. This construction of new roads is what TomTom has a temporary strategic advantage over Apple (only temporary since Apple could get a department together to monitor all new roads).
The other thing you ignore is that people want their local data to be correct in the maps they use, for practical reasons. I too reported new construction around my home everywhere I could, because it's, among other things, in my best interest to have my address easy to find (by guests or postal drivers, for example) on any GPS out there.