Why did not Athena send Odysseus directly into the city?

Odysseus would have been ambushed had he arrived in Ithica without a disguise.

Also a large part of Homeric Greece was reputation, and making sure that everyone knew of your great deeds. Because Odysseus was able to survive these hardships and brave feats, when he did eventually return, everyone would learn of his bravery and heroic adventures. Basically, they loved to show off, and in their society, there was no point in doing anything if no one else knew about it.