This is very true. I have a hard time getting along with these kinds of people in general because they are such an energy drain.
The arguments are often very poor, too. You can provide a million reasons to back up your point, and they knock it all down with "no that's unrealistic" or the recently very popular "that's unscientific"... without providing any explanation or resource implying any scientific basis for their point. Or, if they do, it's unspecific, outdated, or a poorly executed study.
People these days, especially those currently 20-40 years old, like to hold opinions and outlooks they think make them look smart or realistic. In their minds, cynicism and shouting "SCIENCE!!!" at things, no matter how unfounded, is what reason looks like.
It's extremely irritating.
As for solving problems: It is good to recognize that a problem exists, but an optimist can do this too. The difference between an optimist and a pessimist is that an optimist has the mentality and energy required to actually solve the problem once they recognize it. A pessimist is more likely to not try on the basis that "it won't work anyway".
Optimists and pessimists are equally likely to overlook things and important issues. The thing that determines your ability to spot and recognize problems is your observatory skills, not your attitude in life.