Maybe the CIS doesn't seem to be moving to you because they are blocked by the Republic. The CIS can't move very fast since they have to fight their way through the Republic fleet which would slow anyome's pace, while keeping in formation around their flagship which seems to be a sphere to protect it. If they ram their ships, then they will be knocked out and can't defend the flagship, not the best plan. We can also ask why the Rebels didn't bomb or ram the second Death Star by that same logic. While the Republic ships have to fight through this school of CIS ships to reach the flagship at the core. We clearly see a line of Republic ships slowly piercing their way through the CIS fleet, the setup of this battle is going to lead to ships becoming intermingled as a outside group has to fight their through another group to it's core. We also see as Anakin and Obi-Wan fly though the battle torwards the CIS flagship, we see less and less Republic ships and more and more CIS ships. By the time they reach the flagship, there are no republic ships to be seen in the background. This shows that the Republic, other than the two Jedi, haven't breached though the CIS fleet yet. Both sides seem to be blasting each other to reach their goals, the battle is pretty much two blockades trying to force their way through each other. I think the Republic ship that broke though into the core was only trying to disable the CIS flagship, but we see a scene where the clones hit one of the Invisible Hand's gun magazines which blows up and sent the ship crashing. Until that scene it looked like the Invisible Hand was beating the Republic ship. They showed the CIS was using Shells instead of lasers for a reason. While I agree with you that the Rebuplic would need to form a sphere to block the CIS fleet from escaping. The same is true of the Battle of Endor, since the Imperial fleet should have formed a sphere around the Rebel fleet and their second Death Star (so it can blast the Rebels), but we clearly see this doesn't happen. Also why send your fighters to be intermingled with the large emeny ships you plan to blow up with a Death Star so they get blown up too? Seems pretty wasteful and foolish. All the battles can be nit picked to death if we want to.