The question at the seminar was asked "Why would I do this". Well the answer is a simple one too. If you are emailing people over and over again what YOU want to tell them and they are not taking actions, it would suggest that you do not have campaigns that are currently relevant to them. So by continuing to send them your emails you are just reducing the chances you have to engage and convert them into sales. Now they may be past purchasers and not in market right now for what you have to offer.
Essentially what you are doing with the break up email approach is to try and reconnect with your database. Why not ask them to update their profile to make your future messages more relative to their current needs. Don't use their last purchase entirely as a guide for future purchases from you. People change. So you need to have a relevant Customer dialogue to find other products to promote or get them excited to move on a new larger purchase down the road.
If you are not having a two-way conversation in email, you will find that your campaigns are slowly losing steam and not driving results.
Why not use the holidays to approach the new year in a way that helps you while at the same time builds a program based on need with your subscribers. Or you could continue to send email campaigns and hope for the best while your subscribers lose interest. Its your call.