explaining this or that could happen and we just won't know until we find out some other fact. All true but not stuff for the customer. who just wants a date that it will be done.

And in there/our defense am reminded of a doctor (sort of the same thing) telling the journalist that some process cures a kind of cancer 60% of the time but you have a bad reaction 20% of the time. The journalist kept pressing "So, you've found a cure for cancer"?
Doctor "No, 60% you have this good outcome and 20% of the time you have this bad outcome"

The problem comes with the non-engineer who promises that they can get it done in some way short period of time. So they get promoted and are out of there in 6 months...even though the project still isn't done, but the engineers get the blame for not solving the problem in the time period that the political type promised.

No wonder we're bitter.