Question: According to RAW, should forcing stuck/locked/barred doors open be a Strength check, or a Strength (Athletics) check?

As I read the description of the Strength ability and the Athletics skill in the rules, it seems that brute force checks, such as pushing/shoving/kicking or pulling open a stuck, heavy or locked door should be a simple Strength check, with the Athletics skill applying only to things that involve more coordination such as jumping, climbing, or swimming.

However, in the published Dungeons & Dragons adventures, examples are inconsistent. Other than the Starter Set, where all door checks are just Strength and all Athletics checks involve climbing or other more complicated activity, other supplements seem to contain a mix of Strength or Strength (Athletics) to force open doors, seemingly at random within the same adventure.

For example, in Curse of Strahd area K74, opening the 5-foot-submerged iron gate to a row of cells requires a DC 10 Strength (Athletics) check, but opening the 5-foot submerged locked/barred gate to any particular cell is a DC 25 Strength check. The only difference is the latter is locked. But then in K78 opening the locked door is a DC 25 Strength (Athletics) check, so being locked/barred isn't the determinant.

What do the rules specify should be the standard check to force open a door, gate, portcullis, etc.? When do they say Athletics skill should apply, if ever? I'm not asking about DM preference (because I realize any DM can vary any rule any time they feel the need), but what the RAW and RAI state, and if there is any rules-based explanation for the noted exceptions.

Answer: 
I would (and do) apply the Athletics skill. Characters don't get a lot of skills, so it's an investment to choose Athletics as one of the (about) 4 you get. So it should be of some use.

The entire point of the Athletics skill is that you are better at physical tasks, Opening (stuck, locked, etc.) doors is a physical task. So if a character has invested in the skill, he should get the benefit of that.
Personally I always let people add their applicable skills. It makes more sense that someone who trains in lifting things (which is part of athletics) would be better at lifting a portcullis than someone who isn't. They would probably also have an easier time opening a stuck door. If someone puts one of their limited number of trained skills into something, I'm going to give them the benefit of using it if it makes sense to do so. That is just my personal GM style though.