PLA fillament is very prone to heat transfer, and when it heats up, it tends to expand slightly. What happens is that the barrel gets warm enough over time and heats the PLA over enough surface area that it will cause the PLA to expand and sometimes lock in the extruder bore. Adding additional cooling keeps the upper end of the fillament cold enough that it won’t jam before it gets to the melt chamber.
There are other fillaments, all of them with their own unique challenges. I print mainly in ABS, and it is possible to print large things with ABS, and print them well. PLA is probably an easier starting material to print large things with though, on account of the whole “ABS tends to lift and warp unless it is in an enclosure” thing. ABS does not need a cooling fan to print well, and the stock TAZ fan will work forever with ABS filliment. It has its own issues but Bore lock isn’t one of them.
HIPS plastic can be used for printing as well, though it will disolve in certain citrus based solutions. It’s basically the worst of both worlds of PLA and ABS to try and learn with so I would avoid it.
The higher temperature fillaments are also usable, and you can make large things with them, but I wouldn’t reccommend them as your first fillament due to higher temperature and complexities in printing them.
PLA is probably going to be your easiest option to start printing large, not particularily strong or heat resistant objects. ABS can be a pain to learn at first but once you master it, you can print things like a trombone, or a small ROV with it (http://www.thingiverse.com/thing:451236) .