DC 25-30 is quite doable if you are specialized for that skill with high attributes, advantage, expertise etc. The 15 +/- is quite fine if you just have proficiency. 10 is for non-proficient checks. 99DC is obviously a joke.
Really don't see the problem or point of this rant at all. Some skill checks are supposed to be a long shot, and that's fun. I've had a critical success on a DC out of my range and it was a real hurrah moment. The DC would've been very fair if I was specialized for it though, which is the point of specializing in skills.
Seems like you'd rather not have skill checks at all and just always be able to succeed at everything.
