Developers can often get over-excited about their game -- which is understandable since it's often a passion project. It's similar to a new restaurant owner with plans to have a franchised brand. Long-term goals are great, as long as you can still complete the steps to get there.
Game designers can sometimes promise a lot of features and concepts for a game that doesn't even have a working build. When you invest in a game, and the developers announced they've scrapped plans for a console release to focus on mobile, or change the game from a single player story to a multi-player experience, this essentially changes the idea you put your money into and creates uncertainty.
If they made one big change that doesn't seem to match what backers signed up for, how do you know they won't make more?