Not sure I agree with removing the message altogether. I personaly haven't received it yet, but as I just recently attained level 10 I'm sure I might start seeing it.
While I understand the desire to deter people from shelving a character when they hit the cap as well as deter them from playing their character differently because of the cap, I think a lack of communication about where one's character stands in regards to receiving XP is ultimately more frustrating and more likely to create annoyance and misunderstandings.
I just find that removing tools for communication in the hopes that it will cause people to behave differently when they don't know something often don't work as expected and just engenders more aggravation. I think it would be better to raise awareness and understanding of the cap as well as perhaps re-wording the message if necessary.
It's going to happen, regardless of anything that is done, that people are going to use an OOC considersation such as being at a cap to influence IC decisions, just as people make up IC reasons to go into a dungeon that they are sure will give them enough XP to level them when they get close to level ("New Paths of Enlightenment" message, which I personally find to be okay in most cases, just because levelling up isn't one's prime motivation for playing doesn't mean one shouldn't do things to push them up a level when appropriate). Shelving a character I think is unnecessary and while I can understand the frustration that would lead one to do that, perhaps one in that situation could challenge themselves to change their perspective on things. For people whose primary motivation for playing is to advance in levels, I think they're destined to be frustrated in a PW such as ours where the reasons for playing are far deeper than merely advancing to the next level.
Personally, I wouldn't totally cease playing Damiana for a length of time if she hit a cap because I play for the immersion, story and RP and take a lot of enjoyment from that, regardless of if she's advancing or not. Now, that said I do have an alt and in all honesty I'd probably give that alt preference unless there was some plot or other IC reasons for Damiana to be present. As it stands currently I don't have Bastian involved in too much as he's still a new character whereas Damiana is quite busy and involved in a few plots. If both were equally vested in plots and situations and one was capped while the other was not...it'd come down to which plot I wanted to be a part of at that time.
It also comes down to who I feel like playing upon logging in.
That's my take on it, not saying it's right, wrong or that anybody else should have the same view.