That's why most people use external displays and a proper keyboard. This also allows for a more ergonomic workplace. There is nothing more important than that.
The display on a notebook is only going to be a real problem if you are programming a lot on the road. In that case you'll have a very complicated problem because you have to find something that is easy to carry around but still has a lot of screen real estate. You may want to rethink how you work on the road so it matches the screen real estate of whatever MacBook you'll end up with. The fullscreen mode and tools like bettersnaptool can help.
Btw, a display can be too big too. The problem with big displays is your ability to track what is where. When you have to continuously orientate where your stuff is on the display it makes working on it annoying and difficult to concentrate. That's why I switched from dual screen to single screen at work.
This is all personal choice. People are comfortable with what they are comfortable with.
If anyone could use a desktop 100% of the time they would buy a mini or a pro. This thread is about a laptop which implies (and was articulated) a level of portability.