Another thing to think about when going larger for the sake of bigger single-piece prints is the increased loss from failed prints. If you can break the design into smaller prints you reduce the risk that failure of a single print will scrap the entire assembly.
Unnecessarily going bigger has its drawbacks. It will add mass to the x,y mechanism, which can negatively affect print quality due to momentum.
Larger build plates are subject to more warpage and longer warm up times to dimensionally stabilize. Higher energy costs.
You are absolutely right. However, there is a place for both.
On the plus side of going big, single large prints are normally stronger then multiple joint pieced unless you do extra work to design the joints or are using some exotic glues. You can absolutely design joints that are as strong or in some cases stronger than a monolithic piece, and there are glues that have bonding strengths higher the material strength. However, that is time, energy, and cost.
If the part is cosmetic, a single print normally looks better. Saves time and effort on finishing.
If you are many small pieces going big is also a benefit. My 400x400 has 77% more printing surface then a 300x300. That equates to a lot more parts per print. That generally equates to higher productivity. It is also nice to be able to print all the parts for a project in a single go vice having to print a few parts, comeback in a few hours, clean the build plate, wait for it to heat up, makes sure the first layer prints, print a few more pieces, repeat in a few hours.
Finally, some cool parts just can't be practically broken down. The effort to align blind internal features or the risk of leaks just isn't worth it.
I have evolved through printers. I stated with a monopart mini. It was tiny, even when I moved up to the Ender3 Clone, I still often used it for small brackets or clips because it printed faster. Until I tore the Ender apart to upgrade, it still got used fairly regularly. It was slow, but because it was slow it didn't have ringing issues and was very forgiving. For cosmetic parts sometimes it was easier just to run it then to tune the RatRig if I didn't have a good profile for the filament.
