Use the High Level Rules.xml instead of the DefaultItemRules.xml
Edit: The High level Rules don't pick up magic / rare items lower than lvl 61 tho. If u want the bot to pick up all blue and yellow and vendor them , and keep all legendaries , then do this.
Open your DefaultItemRules.xml and scroll down till you find
<!-- Keep rares and legendaries, regardless of stats. -->
<ItemRule ruleType="Keep" description="Rare and better items!">
<StatRules>
<Rule stat="Quality" value="Rare4" />
</StatRules>
</ItemRule>
</Category>
And simply replace "Rare4" with "Legendary"