There are already big printers on the market. Powder printers are very mature and can get rather large. They are used in manufacturing and cost tens of thousands of dollars. I'm sure this isn't the big we are talking about though. We're talking about filament printers.

When I got my first printer it seemed really small and since then I have built a bigger one. However, there are serious drawbacks to larger printers:

1. They require much more stability to print accurately. You will need stiffer/thicker frame parts and more precision movement parts.
2. The above makes them considerably more expensive.
3. The time required to print "big" parts is excessive. Also, imagine how many failed prints you have when printing small. Now scale those numbers up when you have a part that is taking many hours to print. You are talking lots more plastic waste now.
4. Add larger heated beds into the mix and you need some serious power above what a standard household jack can provide.

Those are just a few things that I think of when I think of going big. We can easily scale up any printer. It's only a question of money. But we don't actually end up with a printer that is up to the job. All the same issues with small printers are just amplified with bigger printers. Before going big we need to come up with printer designs that are going to print over and over again without failures or misalignment. At home, what we really want is a large box that has a single button on the front. Press it and out pops what you want. I don't think big will be plausible for home until we get there.