Inventing a lighting control system only you and family know how to control would frustrate intruders, but it would also frustrate first responders. And guests.
To me, it violates a basic tenet of architectural design, which is that a home and its features should feel comfortable and accessible. Lighting is part of what makes a space habitable. You know what it's like to grope for a light switch in the dark, even in a strange room you have pretty good intuition of where to reach. Good design supports that intuition, bad design doesn't (this video is amazing).
Those remotes are not an awesome feature. They are included to make fans cheaper and work in sites not wired for fan+light. Precisely because of that cheapness, I tend to think of remotes as kinda lowbrow. You might consider this guy might've bought some pretty nice fans if he's a zealot. See if they have any resale value and sell them with their matched control switches.
I agree you shouldn't need a whole stack of switches. Keep at least 1 switch intact for powering the fan and light. For one thing that spares you the struggle of finding the remote in the dark, being caught off guard if you run out of battery, etc. It also gives you a way to de-energize the fixture if it has an electrical problem.
There are several other ways to control fans without a bevy of controls. A lot of love has been put into this field.
If the cables will reach, you certainly could remove the n-gang box and replace it with a 1- or 2-gang, so you don't have enormous cover plates that are mostly blank. You will be obliged to to so anyway under the electrical code. NEC 210.70a1. You need a light switch at an entry to every room.
210.70 Lighting Outlets Required.
Lighting outlets shall be installed where specified in 210.70(A), (B),
(A) Dwelling Units.
In dwelling units, lighting outlets shall be installed in accordance
with 210.70(A)(1), (2), and (3).
(1) Habitable Rooms.
At least one wall switch-controlled lighting outlet shall be installed in every habitable room and bathroom.
If you are caught having downgraded your house below that minimum, you don't get to roll it back to status quo ante. You will need to update to current code. That'd be a big job since code now requires neutral at every switch loop, and some municipalities require 3-way switches at every entrance. Both of these requirements could necessitate pulling more wire, including 14/4 for switch loops.