99% of users have 0 use for a quadcore.
True, but it's not a reason not to offer the option to those that either want it or could benefit from it - it's the whole chicken or the egg story all over again. Hence why it was nice to have a cheaper dual-core option and a pricier quad-core one. Now we only have slow dual-core and normal dual-core options.
If the main idea is to make the Mini so unappealing in order to discontinue it and push potential buyers towards the MBAs and the low-end iMacs, they're doing it super well on that end.