I think one of the confusions that come along is the definition and use of the word MODULAR and whoat it means.
You can have a MODULE, which is a container that can be moved around. I think most of us understand what these are, freight cars, semi-truck trailers etc. They come in a variety of sizes.
Then you have a MODULAR design feature within a starship - this is NOT a module. It is a design feature that allows you to quickly convert an interior space from one configuration to another. The walls are moveable, furniture is quickly replaceble etc. So, you can convert a Modulear Space from Cargo to Passenger configuration in a few hours.
These are NOT the same thing. although I have to admit, I tend to mix them up too.
The Cutter does not carry a module, it has a designated space that is quickly convertable, so you can carry passengers or cargo or whatever mix of that you want. It is NOT a hull with some kind of clamping system that attaches to a Module and carries it around.
The standard design shown does not carry a module, it is a modular design. Even the writers and designers of the official books have mixed these two ideas up. Offering alternate module designs and costs etc.
Personally, I think it SHOULD carry a module. IMTU, I use it that way - if you build a ship using the Modular feature, it means it carries modules. Under that concept, you could have a Cutter with a Module and 3 other modules which could be swapped out as needed. That design makes sense to me. A modular design, as described does NOT seem to justify the cost as written.