Several of us do tend to utilize larger designs than most of those commonly posted, particularly for commercial class vessels. However most do not jump straight to using the behemoth type ships immediately.
For example, here are the typical sizes I use for military craft in most games.
FTR Fighter [250 ton]
FTR-B Fighter-Bomber [250 ton]
FTR-H Heavy Fighter [500 ton]
FTR-HB Heavy Fighter-Bomber [500 ton]
DRP Dropship [500 ton]
AWACS AWACS Craft [500 ton]
GB Gunboat [1k ton]
COR Corvette [2-9k ton] - applies to any ship between gunboat and frigate
FR Frigate [10k ton]
FR-H Heavy Frigate [20k ton]
DE-L Light Destroyer [30k ton]
DE Destroyer [40k ton]
DE-H Heavy Destroyer [50k ton]
CR-L Light Cruiser [60k ton]
CR Cruiser [80k ton]
CR-L Heavy Cruiser [100k ton]
CR-B Battle Cruiser [100k ton] - Lower amour/weapons, more speed.
BS Battleship [150k ton]
DR-L Light Dreadnaught [200k ton]
DR Dreadnaught [250k ton]
DR-L Heavy Dreadnaught [300k ton]
DR-L Super Dreadnaught [400k ton]
MON Monitor [500k ton]
MON-H Heavy Monitor [600k ton]
MON-S Super Monitor [700k ton]
TTN Titan [1000k ton]
LVN Leviathan [1500k ton]
Fighter wings consist of 5000 tons of craft
CA-P Pocket Carrier [20k ton] - 1 Fighter wing
CA-L Light Carrier [40k ton] - 4 Fighter wing
CA Carrier [80k ton] - 8 Fighter wing
CA-H Heavy Carrier [200k ton] - 20 Fighter wing
CA-S Super Carrier [400k ton] - 40 Fighter wing
Jumping straight to the higher sizes of craft via using hab-modules to let industry build them does suffer some disadvantages.
First and most obvious, the hab-module is taking up space and crew that could be used for other things.
Second, if you are sidestepping waiting for your shipyards to reach the appropriate size, you will likely not have the maintenance facilities to support the larger ships without having to expend large and increasing quantities of maintenance supplies.
Third, lacking the appropriate sized shipyards means that they cannot be refitted as your technology advances.
Fourth, there is a hard limit on how big your ships can be if you don't want to be reliant on jump-gates for inter-system travel, that only reaches over the million ton mark at the end of the tech line.
Fifth, if your factories are tied up in building your ships, they are not working on expanding your industrial capability/mineral income.
Some of these can obviously be ignored for purely commercial ships such as terraformers, and of course you are always free to ignore them to play in a particular style, but they do explain why many stick with the smaller designs.