Is it ok to have braces even if you lose 2 molars?

Yes: Certainly if it improves your over all condition and help your teeth on a long term basis.

Yes: You can still have braces even if you are missing teeth. Braces can put the teeth where they will look good , function better, and are in the optimal position to, have your missing molars replaced. This would need to be planned before you start treatment so talk to both your general dentist and an orthodontist so they can work together to give your the best treatments. Preplanning is important.