Do I have to do squats if I want nice legs?

No, you do not have to do squats. There are a lot of exercises you can do instead of squatting if you are unable to do squats. Leg presses, lunges, step-ups, and various other movements will all work the same muscles. Basically, a squat works your hip extensors (glutes) and knee extensors (quadriceps). Every leg exercise is a variation on this basic, everyday movement. You squat to sit and stand up and any other time you need to get closer to the ground to pick things up. Most people envision a squat as using a lot of weight on a barbell behind the neck. Admittedly, this is uncomfortable for many and can be particularly stressful on the neck. It is perfectly reasonable to squat in a machine, while holding dumbbells or even using cables. Lunges, in particular, are great because you can add external resistance if needed and they can be performed in a variety of ways that stress different muscles than a traditional squat.