That seems to be a misunderstanding of the nature of a UUID. Simply replacing the model with the UUID provides no tracking in this use case, as it's a single purpose reference.
If you propose that they generate a new UUID on every ping the OS makes, then you'd be able to tell how many unique installations are active on any given day, but you wouldn't know how long they had been active, nor would you know what model of computer they were, nor would you be able to know how many were active for a longer time range such as a week or a month.
http://en.wikipedia.org/wiki/Smolt_(Linux)
The data is aggregated for reporting: