Yes thats the bottom line.
If you like wearing jeans, do so. If you don't own any or dont like wearing them at dinner or in x situation - don't.
Just don't expect everyone else to adhere to your own personal dress code - which I'm not saying anyone on here was doing, but sometimes you do read comments saying that sort of thing.
I read an old review which said they were disappointed Scenic dont enforce jackets at dinner - which is really silly, since the dress code is clearly stated as casual.
I guess if casual clothing of others is a deal breaker for anyone, perhaps river cruises are not for them.