You certainly could do a full wort boil with extract. In addition to increased hop utilization, you might also see some slight color impact, depending on how concentrated your partial boils were. In general, you could expect a slightly lighter final wort color with a larger boil volume due to a reduction in caramelization in the kettle. For most beer styles this won't matter much though.
One potential drawback of the full boil, is that you now have more boiling hot wort to cool before you can pitch your yeast, so you chilling times will increase compared to topping off with cool tap water. You may find the increased time worth it if the finished beer tastes better.
The Homebrew Nerd