Technology moves fast. It wasn't all that long ago that the 2AA-cell Maglite was the smallest, brightest flashlight you could get, and it was still a (by today's standards) large, weak light. Sure, other lights were more powerful and/smaller, but the cost was prohibitively expensive and they ran on these obscure batteries that also cost a bit more than AAs.
Fast-forward to today, and we have pocket lights like the 5.11 Tactical TMT Plx Penlight available. With 90 lumens (compared to the Maglite 2AA's 14) in a flashlight that takes 2AAA batteries, this miniscule light is big on power. Run time is listed as 4 hours and the beam projects to almost 100 meters, and the PLx is water- and drop-resistant.
Finding the right balance between size and power is a struggle for any item you consider for your EDC (Every Day Carry). Too big and you leave it at home; too weak and you don't see the point of having it (and therefore leave it at home). Any item—be it flashlight, pocketknife, firearm, etc.—has to be in the "sweet spot" for size (fits in a pocket, etc.) while retaining enough power to be useful. The PLx hits that sweet spot pretty well—it's small enough to fit unobtrusively in most pockets, while offering plentiful illumination.