Slogans are all very good, but if we are bombarded by them, or just with the passage of time, they can turn into clichés that no longer serve their original purpose. Other things can happen, like they can start to mean different things to different people (e.g. insiders vs outsiders), which again cause them to be ineffective or worse.
We sing "We want Moshiach now" and put slogans on yarmulkes and elsewhere but what does it really mean? Indeed, we mention it so often in shmone esrei that most people just rush through it without thinking twice, and others need convincing that the desire for Moshiach is not exclusively Chabad's. Certainly saying something (different) about Moshiach & Geula on a regular basis can help break the rote patterns and actually get us thinking.
