This question is asked a lot by fans. Why do power rangers usually dress according to their colors?
The answer is simple. Most likely, it is to help kids identify who is which ranger. After all, "Power Rangers" is primarily a children's show even though there are older fans who still watch it. You may argue that kids are smart enough to figure out who is who for themselves, but not everyone is like that. Some people are slower than others, so the colors are very helpful.
In the real world, if heroes want to keep their identities a secret, they should not be wearing their superhero colors in their daily life. That brings me to a second reason why rangers wear their colors. Except for teams like Lightspeed Rescue (who show their identities to the public), it does not make sense right? Well, it's just a cool aspect of the show. You may or may not like it, but for some of us fans, it looks nice to see the rangers wearing civilian clothes matching their ranger colors. Sure, it's not realistic for the story...but it's a tradition. For me, Ninja Storm and Dino Thunder had the best wardrobes. Whoever was in charge of that had a really good sense of fashion.
There have been some instances in which the rangers wear totally different colored clothing that features only a small hint of their ranger color. Take a look at this photo from the 15th anniversary special team-up "Once a Ranger" from Power Rangers Operation Overdrive. The only yellow that Kira Ford (Yellow Dino Thunder Ranger) has on her are her belt, bracelet, and morpher.
It's great to see them stepping a little bit away from the tradition every now and then, but not completely. As long as the ranger color is somewhere on the actors, whether it be their entire clothes or on a single bracelet, I think it would be fine. I love it when they represent their ranger colors!