I think we all agree with that premise but wonder why that it is.
It's a consequence of the uncertainty principle. In the first experiment, (Without the observer) the position of the electron is uncertain (We don't know which slit the electron went through). that allows for a less uncertain momentum which is the same as a more shaply defined wave-length (By the de Broglie's relation p=h/lambda). This shaply defined wave-length leads to the observed interference pattern.
In the second experiment the position of the electron becomes more determined and, by the uncertainty principle, its wave-length becomes blured (more uncertain) destroying the interference pattern.
Maybe its just not possible as of yet. I mean, who would have thought that matter behaved like a wave function or that by trying to observe the phenomenon would actually cause it to behave differently than when not directly observed?
I don't think so. the validity of quantum mechanics (QM for short) has been confirmed by a huge range of experiments to the point that it is not unreasonable to consider it incontrovertable.