My wife sometimes calls me a "dream killer." Not my favorite nickname, but I get it. I tend to be overly pessimistic in my interpretation of "being realistic." It's really not all negative, but there have been times on the occasion where a pretty decent idea was shot down. Whether there's a logistical fallacy associated with the concept or it just doesn't seem feasible at the time, my opinion doesn't necessarily mean the idea is actually bad or not worth pursuing. It may need some tweaking to refine it into a truly great idea.
We get a lot of prospective clients that come to us with all different kinds of ideas. The creative nature of our industry tends to lend itself to the pursuit of innovation. While some ideas we get sound a little quirky or unrealistic, I am a firm believer that there is always a way to massage an idea into reality.
If you believe you have a great idea, it's your responsibility to execute it into reality. But, that doesn't mean peer research is off the table. Take criticism into consideration when pursuing your idea. Consider what criticism is just chaff and what criticism is constructive to your root idea. But don't let that criticism destroy your idea. Figure out a way to make it work.