No, lens flare is NOT a 'good filmmaking technique'
When occurring naturally, lens flare is awesome. It can make all the difference in a beautiful picture. It even adds some scope to shots because even though we don't see lens flare with our own eyes, we're used to it appearing on camera.
The problem is when some jackhandle drops it into EVERY scene using EVERY possible light source. This is a sign of someone who has nothing else to offer, and it's the kind of cheap trick people use who don't have any idea what they're doing. It's distracting, it's ugly, and it can make the shot hard to figure out because you can't actually see any details because the shiat is all washed out and covered in glare.
B&C is probably one of the worst offenders I've ever seen, the lens flare BS almost made this unwatchable. I don't know who made the decision here, but they obviously went to the JJ Abrams' School of Making People Believe That You Know What You're Doing(When in fact you don't). Hell, this guy probably got his Masters' in cheesy bullshiat.
When it gets to this point, lens flare is nothing but a crutch.