Two and a half centuries ago we allowed the government those powers
No, actually. All governments before that have always asserted the right to search anyone and everywhere. We didn't "allow our government" to do this or that — we explicitly disallowed everything else. This may seem like hairsplitting, but it is historical truth — and you seem like you need refreshing of your perspective...
The sort of crimes the NSA catches have nothing to do with you and I in our daily lives.
NSA is not going to ask for a warrant any more than Alan Turing was asking for one, when he monitored all radio traffic he could — in an attempt to catch the enemy's transmissions. That organization's activities are beside the point, really — as long as they don't prosecute in US courts.
There are, unfortunately, a large number of other crimes, which the bad old eavesdropping helps solve/prevent — whenever the bad guys need to communicate, law enforcement has a legitimate need to be able to listen. Few of these crimes are Internet-specific — the same things we are discussing with regards to the Internet have been said back and forth decades ago about telephone.
They protect megacorps [...]
Oh, sorry, I didn't notice, you are an "anticorp" sort — I wouldn't have bothered with such an idiot. One percent much?
But now that I typed most of the answer anyway, you may as well have it. Remember to logout and, please, don't hate.