[KozmoNau7]

Why even bother with overwriting the data if you're just going to physically destroy the platters and/or heat them beyond their curie point anyway?

[FooHentai]

Timeliness, usually. Destruction is usually a batch job so if you care about risk of data exposure in the time lag between being able to wipe the drive (usually an online, relatively low-hassle activity) and destroying the drive, wiping is worthwhile.

Again, thread modelling is crucial. There may be no point wiping!