I sent an email to Writer’s Market support on March 7th about not being able to add markets any more and on the 9th I got a reply, a very personalized, polite reply. I will share part of that here:

We’re currently fixing a huge customer database/customer service application tied to WritersMarket.com, which will significantly increase the customer service aspect of the site. When that is finished and tested (currently projected at 4/15-4/20), Add-a-Market is the very first thing on our list. It’s a much smaller job compared to the customer service application; so it should be done fairly soon after that mid-April customer service deadline. I know that still feels like a very long time (at least it does to me), but we are working to get it on there asap. In fact, we’re planning on adding it to the favorites folder part of the site, so that you only have to “add-a-market” one time, even if it’s one you submit to multiple times, and that will also allow you the ability to keep all your favorite markets together, whether they’re listed on our site or not.

That seems more than reasonable, so my current plan is to renew my Writer’s Market account and use it — but also report my stats to Duotrope and make donations there, because I really enjoy being able to see each market’s average response time and acceptance ratios.