Did I need a root canal based on my X-Rays? Seeking 2nd opinion. I recently visited a dentist for a routine check up. (photos)

These radiographs are a little blurry when scaled up to a readable size just from the copy & paste process...however, based on just these images alone, it does appear that there is some deep decay on your lower molars, and there does appear to be some evidence of inflammation around the roots that correspond to these areas of decay. If this is the case, then the appropriate response would be to perform a root canal. Greater detail is necessary in order to say whether you have other areas of decay. 
It is very common to see multiple errors in a "full mouth series" of radiographs like this, but these have everything we look for in a good diagnostic quality xray. They appear to have been taken in an office with a high standard of care. There is no indication that your doctor is being less than truthful with you. At the same time, I believe you should seek a second opinion when in doubt and that your doctor should not be offended, but instead should encourage you to do this.
Be cautious when considering what you read about root canals on the internet. There is definitely some crazy information out there that is not base on science or research. 

Unfortunately it is very difficult to read your xrays in the picture. It is not uncommon for a tooth that has no symptoms to need a root canal once the decay is removed, if the decay is very deep. Xrays often don't show the true picture of the decay because they are a flat view of a three dimensional object. Root canals are an excellent way to preserve a tooth that is very decayed. The other option would be removal of the tooth. I'm sure your dentist is looking out for your best interest. If you have concerns about your treatment you could get a second opinion.