The important point here, is that while we can now cite pocket projectors that claim 100 or even 200+ lumens, those models generally do not offer battery operation, or if they do, it's going to be a hefty external battery pack. To get out 100+ lumens you need some sizeable batteries, and those batteries alone, are physically much larger than today's pico projectors. I'd go as far as to say that the AC power supply for the LG, is probably 5-8 times the physical bulk of the smallest picos like the PK201. Going forward, we will need much smaller batteries than today with the same amount of juice, or we need to make the pico projectors far more efficient. Most likely we'll need both.
While all of the picos can actually do a reasonable job on a sub-40 inch diagonal screen, in a dark room, there's a long way to go, for example, before the typical pico can do a competent presentation in front of a half dozen folk. That doesn't mean that there aren't a lot of applications you can use one for, from gaming, to watching youtube and other movie type content, and viewing photos and documents.
I do, however believe that for this class of projectors, battery power is almost mandatory for success. Perhaps adding an inch to length and 1/2 inch to height would allow a big enough battery to get us to that 40 - 50 lumen range that I think most people would be fairly comfortable with for this class of product.