Because the world changes, and they refuse to bring in outside perspectives and hire new people. It's the classic 1980s view of the world from Detroit, why worry about Japan, they make crappy cars....and, I'm tired of the "they picked late" argument. Philly has had no issues drafting great players recently (that they then trade for proven players). There is no natural down cycle that explains three years of zero legit MLB players coming up, that's just bad development. I agree it is a lot harder to build a team through the draft when drafting late, but that's their philosophy pretty much, to build through the draft or by signing older players. So if that is your philosophy, you need to EXCEL at it, not be average, or the same as everyone else. You need to be great at it, and they haven't been.
Why so glum? Look at the last three years (counting this) and who has come up, and look at AAA and AA players, and tell me, why should I be hopeful this year or next? I'm glum because I like it when they win, and I don't see that on the horizon, unless they significantly change their modus operandi.