If there is another broadband providor in your area, then make sure you switch, if you do not then it is your fault that that ISP's are adding bandwidth caps.
It doesn't matter if you use all of the bandwidth or not. Because just like other resources (bandwidth is a unlimited resource, speed is limited and is why you pay more for faster speeds)
Even if you don't use all 150GB, now, will you be able to say the same a few months from now, will you still say the same a year from now?
In the words of Bill Gates a while back, No one will ever need more than 640K of RAM (Imagine if a 640K RAM cap was set)
While many users will use around 100GB, not as many are using 150GB today, but as the internet changes, so will bandwidth usage, and bandwidth caps are an attempt to make sure that you wont use those new technologies because current ISP's oversell ther service (selling more speed than is actually available)
The reason why their current method of overselling works is because services that do not benefit or need the all of the speed you are paying for are widely usedd (so the average user who uses very little will also use very little speed (they may have a 20mbit connection but may only use a average of much less than 1mbit/s). And if users wanted to use services that will actually benefit from the full speed of their connection, they would quickly go over their bandwidth cap. (PS most sites will not allow you to load a page at your full speed, (if you have a router firmware like tomato, view your real time monitor and try loading a ton of pages from tomsharsware.com, you will be lucky to even use 10% of your connection speed)
PS low bandwidth caps also open the door to denial of service attacks (a few people in a gaming clan that I joined have had it happen to them) Since the cap is based on traffic going to or from your IP addesss, a packet flood will eat away at your cap, even if your modem is off (as long as the DHCP lease on the ISP end is still going)
One member in another country had a 15GB cap, and as part of a disbute with another gamer, the user was packet flooded and not only was his cap eaten overnight, he also got overages which his ISP emailed him about (though it was too late to do anything about it)
Bandwidth caps are overall bad and are not needed or justified. Data is not a limited resource as a unlimited amount can be created from essentially nothing
Speed is a limited resources and is why you pay for what ever connection speed you get.
What ISP's want to do is charge you more for faster speeds but use caps as indirect censorship in order to prevent you from using services that will make use of the speed you are buying. Think of it as being wowed into buying a car because it is the fastest on the market but the speed limit on the road only allows you to go 30MPH (you bought it for it's speed but you cant use it without being punished)