Are you or Defcon 1 gatekeepers for what is or is not a reasonable opinion? I don't think so.
Seems to me that when someone raises an objection in a largely public forum, that opinion is itself open to scrutiny, judgement, and counter-opinion. This is a discussion board, after all, and not a "I get to say what I want and not have anyone comment on my words" board. If you want that, post it to Facebook or G+ or something and turn off comments.
Using an extreme example as illustration: If you said, "I think I should get into first-run movies for fifty cents," then I think it would be okay for me to say that is unreasonable. I can look at the costs for making films, and for keeping up a theater, and come to the conclusion that the opinion literally can't be founded in reason, as movies at that price point simply couldn't exist. I can look at what people pay for other entertainments, and come to the conclusion that, rarely, if ever, does one get entertainment of any quality for a whopping $0.25/hour, and say that the idea doesn't match up with reality, and call it unreasonable.
So, we can then step back to the case at hand. There is a serious question as to how much entertainment you should expect per dollar spent on game books. If your expectations are too high, yes, I may call them unreasonable.
This place might be a whole lot less volatile if people wouldn't constantly attack the validity of their fellows' opinions.
When your opinion is based on personal preferences and tastes, I won't question the validity. Say, "I don't like what I've seen in the 5e playtests, so I won't buy it!" you won't hear a peep from me. When you start talking about costs, which are measurable and comparable, then we're in another ballpark.