I could not agree with you more. I am not the kind of person that takes purchases lightly. I can get HR to let me buy just about anything but that doesn't mean I am just going to throw checks at hardware when I don't have a full plan laid out. Now there is no harm window shopping to see what is out there.
I think the main problem comes due to a lack of knowledge. So many of us want to figure out things on our own. We think we can design the "perfect" system with little to no help from anyone else. This works for some but I think a vast majority of people rely on vendors and re-sellers to tell them what they need. Many of these are not hardware agnostic vendors so they push a certain technology so they can line their pockets. (Not hating, everyone has to make a living.)
It is our responsibility as IT professionals to take the information given and apply that to our situation. The recommendations do not always align with what the company needs. I feel very happy that I am one of those people that cannot be sold. I have been told on so many occasions that my questions are far more technical than most questions that are asked.
I always play the "why game". Ask yourself why 5 times. If you still feel the same about your intended purchase after you think critically, it is much more likely you will make the correct (and informed!) decisions.