Clone trooper follow the execute order 66 from the chancellor.They almost drive the jedi to extinct.The republic do not necessary need clone trooper.I would believe the jedi could handle the battle against the separatist alone without clone trooper.It would be better if the chancellor and the clone trooper aren't involved.They are evil.
IF it's not because of the clone trooper and senate palpatine,the republic wouldn't has fallen.The republic don't necessary need clone trooper,and clone trooper aren't honest to the republic at all.They betray the republic and almost drive the jedi to extinct.Clone trooper only stay loyal to the senate palpatine nobody else than that.
They are not evil. They simply did what their commanders told them to do. For example, the USA has been in many unnecessary wars that have resulted in widespread death, destruction, and suffering. Does that mean our soldiers are evil? He11 no! They just followed orders!
On a side note, many clone troopers, mostly special forces troopers, did not follow their orders. They deserted because they could not bring themselves to kill the Jedi.
I think that the Clone troopers are definately not useless to the republic. They fight for the Jedi and Senate. Though, Emporor Palpatine was part of the galactic senate (so they thought,) when he gave out order 66, which I'm pretty sure we all know what is means, the Clones simply didn't know better.