I'm not real sure what you mean. . .
Doing full boils is just extremely convenient. You don't have to top up with water, or have several pots heating, or any of that crap. You can just put your water in, bring it up to temp, steep, add extract, boil, add hops and your done. That's the beauty in full wort boils-- plus you don't have to worry much about sanitation issues with cold water additions.
as far as "better results"-- I'm not real sure what implying. . .