Doing this does have a purpose...it can really show the strengths and benefits of different products. It can help answer questions like, do I really truly want to pay twice as much for this camera...what are the real benefits that I'm getting.
On chatrooms, there will always be someone as well who makes a rant about how it isn't the equipment...it's the artist behind the equipment...the camera is only a tool...this always really annoys me. Comparing cameras does serve some purpose and it also does help people make good decisions with their hard earned money. Using a minidv camera vs an awesome camera, the production level of my work skyrocketed. There is a huge difference between watching a cheap film and a big budget...if you turn on the TV it's pretty easy to tell almost instantly whether your watching America's Funniest Home Videos, a big blockbuster movie on TV, or a very local commercial. This argument annoys me, and someone always has to make it; but...there is some wisdom to it.
I think perhaps the biggest problem is when people constantly obsess with getting the best possible image ever...the desire to always have the very very best quality lens or camera in existence. Here's the thing...the general public doesn't really care that much about images blown up 800 percent and analyzed pixel by pixel. Another thing is...right now, unless you're showing something on the big screen...whatever you shoot is going to be compressed for online. Sites like Vimeo have very high quality online video, but it's still compressed. All that pixel watching can instantly become meaningless because your video has to be a smaller file size.
So, image quality does change how people view your film...BUT, with DSLR's, basically all of them are plenty good. I use the T2I, and it's sharp as can be, with beautiful bokeh and color representation. If I had a 7d, could I shoot noiseless at slightly higher ISO's...yes, a little higher. Could I get a sharper image...maybe??? Even after test after test, I am still not certain if there is a big difference in sharpness between 550d, 60d, 7d, and 5d. They have all reached the level that they look so good that the general public isn't going to be like, man I wish this was a bit sharper. For this reason, if you have an awesome DSLR, try to breath and be happy with the camera you have. The quest for the best camera ever is one that cannot be won. I know...it is hard, it is very hard. The 5d Mark III may switch things up and really make an update worth spending a ton of money, but until then...try and really focus on what you have and focus on technique. I'll be writing more about the 5d Mark III speculation soon, it is going to hopefully be a camera worth waiting for. A camera is a tool. Having a sharp sharp camera that shoots amazing images can really help make your work come alive. Having the very sharpest and best camera that exists always...well that is a long hard fight that I would argue really isn't worth it in the end.