Replace the housing?........ bake the headlight open?........ is this your first car?
No you don't have to do either of those things. The low beam lamp is accessible from the back of the headlight. If you have the OEM halogen headlights then you need a H7 lamp, whereas if you have the OEM HID lamps you need a D2S lamp.
For the halogens you pop the rubber dust boot off the back of the housing, and unplug the wiring harness from the lamp. After that you pop the metal retention clip open and remove the lamp. You have to remove the black plastic spacer from the back of the lamp and put it on the replacement one then reinstall in the reverse order. You'll at this point realize that the retention clip was designed by Satan as it's one of the most frustrating things on Earth to reclip, especially because you can pretty much fit a single finger into the back of the light without removing the housing from the car.
For the HID's it's basically the same process, however you'll unscrew the rubber dust cap (vs. popping off a rubber one) and there won't be a plastic adapter to swap between the old lamp and the new one.
If you do run into issues reclipping the retention clip then removing the headlight housing is an option. It only takes about 10 minutes to remove the front bumper and then there are only 3 or 4 bolts holding the housing to the car. A little bit of work doing that can save you extended periods of frustration over not being able to secure the blasted clip.