As we saw earlier, the "Add or Remove Programs" control panel used several heuristics to attempt to determine things like program size and frequency of user. Why did it bother doing this at all?
At the time the feature was added, disk space was not cheap like it is today. One of the problems users were having was running out of disk space and not knowing what they could safely delete. Thus was born the Disk Cleanup utility, which attempted to guide the user through various things that could be deleted in order to make disk space available.
In addition to cleaning up temporary files, you could also remove programs that weren't being used. But how do you know which programs you weren't using? (Maybe you were using a program without realizing it because it ran automatically.) And how do you know how much disk space would be recovered if you removed a program? That's where the program size and frequency of use heuristics came in. By providing this information (or at least trying to), the "Add or Remove Programs" control panel could help users decide which programs to remove.
Of course, nowadays, with hard drives in the hundreds-of-gigabytes range, disk space has become so cheap as to be nearly free. The need to remove programs to make more disk space available is largely gone, but the feature remains as a vestigial organ.