Agree, there are some very tough calls/decisions to be made upfront about aircraft config that you pretty much have to live with until you have the option to refresh the complete interior. Having a standardized fleet is also a massive operational advantage as highlighted above.

If you take the example of BA, a well established operator with years of experience, late last decade management took some decisions to minimise galley space and crew rest space to reduce cost and maximise profits on new planes arriving into the fleet. It's since been realised that actually some of these compromises have impacted operational quality and flexibility, but BA have little option to live with what they ordered.