I don't take them currently because my diet maintains the ones I have just fine. :) A mostly vegetarian diet free of refined sugars (yes I do eat Sugar but only a few handfuls of jelly beans a month. ;) ) allows one to maintain the friendly flora quite nicely. A bit of kefir once a month will help too.
If I get to the point where I catch colds more frequently or digestion slows down, I will supplement. IF I do a lot of cleansing enemas I will supplement.
Mega-dosing the probiotics is good to do when recovering from years of bad diet, candida, IBS, Crohns, digestive complaints, but it's not something to do forever. The goal of any healing protocal is to get to the point where you don't need extra supplementation anymore. Saying you need them forever is rather silly. IF that were true, the human race wouldn't exist! ;)