I run into this too. There are situations where the only way to edit has been double-clicking, so we've generally thought to make it optional only after we make simple edit-alternative to double click. --John Abbe
This issue is a real problem for me as well.
In addition to habitually double-click dragging to select whole words and triple-clicking to select lines, I find myself frequently using laptop touchpads that sometimes mistake a stroke on the scrolling edge for multiple clicks of the left and right buttons. I would rather not have to retrain the whole of my Web usability habits for the sake of a single kind of site, no matter how good it is.
If a situation arises where a card is so misconfigured that the card editor can't be accessed by a page feature, then the card's editing URL can be typed into the address bar.