This sets a TERRIBLE precedent... if you can't win a legislative fight, just abandon your job. Sure, it's just once now, but soon it'll turn into only for "important" bills, and then you'll see it happening for pretty much everything.
Look at what happened with the filibuster... it's become abused to the point that it's now a procedural motion that nearly every bill has to overcome.
I think they're aware it looks like they're being cowards; your reaction is undoubtedly the public's reaction. It just means they think it's important enough that they should do this.
If your reaction isn't the public's, well, then maybe they're doing something right
