And my description addresses that. I even specify that you could give the crew cabins THREE TIMES the size of a typical cruise stateroom, and you'd still have plenty of space.
I think you're vastly underestimating the sheer volume of the Enterprise. If a cruiseship (which as you say ports nearly daily) can carry 4000, surely a starship that is not only similar in length and height but also wider in the saucer section can hold 400 crew plus workstations plus supplies. Which discounts the benefits of the replicator entirely.
A significant portion of the Enterprise is indeed devoted to Engineering, cargo bays, shuttlebays, and other "work" places. I'm sorry you object to the ship needing a crew.
Not to mention two bowling alleys.
The one thing that I can't imagine anyone who knows me saying about me is that I've "underestimated" the internal space of this ship. People might claim that I've "misapportioned" it, perhaps, but I'm not "estimating" it at all. You may have never seen my fully-populated 1701 model (which I've left alone for a while... pretty much after finishing laying in cabins, I got sick of it and it's been on my "I'll get back to it" list for months now).
You might want to thumb through this (now-closed, and pretty old, but not yet "pruned") thread.
http://www.trekbbs.com/showthread.php?t=89810
I'm not "estimating" the internal volume of the ship. This has been a practical exercise.
In fact, it's worth pointing out that my version of the ship is more than 10% larger than the popularly-accepted size, and I've still had to exert some effort to get the whole crew in, AND to have them have places to work and play outside of their cabins.
There's only one really large deck on the ship... that's deck six. And yes, deck six is mainly cabins and crew support. And deck five is mainly officer quarters. Deck four is mainly taken up by medical and life-sciences. Deck three is science labs, including the high-bay lab. Deck two has two VIP cabins, the communications center, and the high-bay lab. Deck one is the bridge.
Deck 11 is basically a maintenance crawlspace, with deck 10 being devoted to tactical systems. Deck 9 is devoted to secondary engineering systems (including exterior hull maintenance systems). Deck 8 has the main computer center, the library computer banks, auxiliary control, and the like.
Deck seven has an outer ring and an essentially separate inner region. The outer ring's usefulness is limited, of course. The inner region includes the transporter complex, the quartermaster's offices (including replication and cargo systems, the central food replication system feeding food slots throughout the ship, etc), and a few additional cabins (mainly for the security team), plus the security offices (including the brig).
There are only a few cabins in the secondary hull, because the secondary hull is largely mechanical... with the ship's keel, the primary engineering systems, the deflector subsystem, the landing bay facility, the main cargo facilities, and non-essential recreation facilities (swimming pool, colocated with the main water processing system, a recreation facility which has a three-lane bowling alley, etc).
I've got the whole thing pretty much laid out. There are some internal details still pending... but the general layout is complete.
My crew cabins are generally 4-up cabins... two bunks for four beds, a common sitting area, and a larger bathroom shared with another 4-up cabin. My senior enlisted and junior officer cabins are 2-up. Only the most senior enlisted (think "Master Chiefs"), and officers of above Ensign rank, get private cabins, with the exception of a few special cases who are required to use their cabins as their offices as well (the quartermaster, who's enlisted, the personnel officer, an ensign, the captain's yeoman, a crewman, etc)
It's pretty well completely laid out. So I'm not "estimating" anything. You may argue that I've misapportioned, and that's fine... but not that I've "estimated" anything.