Yeah while Nami, Chopper and Sanji need to do something and not just become stale they have been here for a while, they are established characters and have done their share of things for years, if people want a SH to do something its Brook that needs it, Franky kind of needed it for a while but he has done a lot since the time skip.
As for the allies guys it’s like every arc, some people didn't like the characters from Skypeia , Alabasta, Water 7, etc. I know this allies actually got to beat important people this time and half of the SHs didn't get to do much but just because you don't care it doesn't mean no one cares, plenty of people here like Sai, Blue Gilly, Ideo and many other of the introduced characters(I'm not going to say Barto and Cavendish because those are obvious) and they like them because Oda took the time to flesh them out, they weren't just "background look cool characters" like in other series and that end up being a complaint in those series because people are like " men he/she was so cool/interesting/wtv but didn't do shit and wasn't fleshed out at all!", I like world building and the fact that we get to know these people backgrounds and some of their character is great, that one of the things I love about One Piece.
That’s why I liked the Suikoden RPG series also, we would go around to different cities/regions, find different characters, from different races/cultures, recruit them and learning about them along the way.
So I do respect other opinions but I like what Oda did here, I don't like that we haven't seen Sanji and the others for more than a year but I have no issue with other strong allies appearing and beating capable oponnents.