Clones are abomination, but they are living things after all. Republic needed coordinated army, not just local in-system home defense fleets, incapable of fighting a war. Separatist threat was growing too fast and there was no time to enlist enough men in both navy and army.
And lets not forget, that Republic was doing almost good before formation of CIS. And, CIS was formed by Dooku. And, Dooku was Sidious' apprentice. It was Sith, who needed clone army, not Republic.
Although, I have to admit - clones have that awesome look despite their anti-camouflaging white armor.