I doubt we'll be changing things just to change them.
A GUI refresh isn't entirely out of the question, but if that happens it would probably be a part of some other major GUI-impacting change (we may suddenly decide to move from PHP to Python for some reason, or move to some sort of MVC framework), and not just because we felt like redesigning the GUI.
We like to focus on making things work properly, and we try not to break things unless they're actually broken/unusable. Opinions on that vary, but it's mostly a bikeshed discussion.
Getting volunteers to code the GUI changes isn't quite that simple. In an ideal world, sure, but in the real world, you may have plenty of volunteers and very little follow-through, or people will disappear leaving code abandoned. If something of that scale is to be done, it would have to be closely handled/managed by the core team with assistance from the community in places.
Any of those kinds of changes would likely be a couple versions out though. We have some other significant work to do in the meantime, but in a version or two we'll be looking for more things to change/implement as the major tasks like updating the base OS, wireless updates, and IPv6 and such are completed.