You stated "rather than" but perhaps having both would be fine.  
I'm ok with changing to just hover (+1), but having both would cater for all preferences.   


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*Alternatively*, if the devs are bored (*`/me runs away`*) perhaps click to show the entire message.   
Like a [JS/jQuery][1] *accordion* style.  

It could drop down into new space.  
And it could return to being truncated if / or:  

 - 10 seconds after clicking
 - Clicking same one again
 - Clicking another one resets previously clicked one then drops newly
   clicked one down

I think with the chat rooms getting more popular such a *feature update* would be welcomed. Given it should work the same across all chat rooms, it's a code-once roll-out-to-many so ROI might be good.  


  [1]: http://jsfiddle.net/aff4vL5g/624/