Nami beating up the crew has always been a gag because she is mostly the straight person of the crew. Nami cant actually beat up Luffy because he is straight up rubber. Battlewise she is probably the weakest in the crew and this is more to balance her role in the crew to get the guys in line.

Without spoiling, Nami is absolutely loyal to Luffy and will have her moments. She will also be shown as a very caring person even to other people she just met.

Remember that Nami literally carried the burden of an entire fucking island.

In short, yeah it improves.