Yes it makes sense. We will add this ("User last seen date") as part of a new query builder for filtering users (it has gotten a very complex thing with mailing lists).

Any other criteria you need for filtering users?

@fplanque great. Looking forward to the version.

Another criteria? What would be fine (but not necessary): selecting users by activity, engagement, interaction.This could offer the option to collect highly engaged users into a special group (A-Users ;-) to deliver special content that probably would be "waste" for C-Users.

Makes sense in bundling valuable users, nurturing them and push their engagement.

How do you define "high engagement" ?

I meant al selected and ordered list, ordered by sum of posts, (meta) comments, messages. or weightend, e.g post counts twice, messages half. Then tick-boxes to activate selected (or so) for bundling them in a group.
But I suppose that the ratio of effort to usage is not economical.

In that case we're no longer talking about filtering but about ordering.

We might indeed order by number fo posts or number of messages. If we start to aggregate with a formula it's a very different beast because we need to come up with a formula that works for everyone... or a formula editor which is nearly insane.