What is the point of the x at the end?

Makes things more difficult for foreigners. The French consider this a feature.

Telling that "eau" is just "o" for pronunciation confuse foreigners even more. Some of then even thinks you are mocking them.

Yet somehow French still manages to be altogether more coherent than English… or at least that’s the impression I’ve had so far.

Being more coherent than English is not exactly a high bar to clear...

(at least when it comes to languages based on the Latin script)

Inferring pronunciation from spelling is very regular in French; the reverse, not so: there may be many ways to spell a sound like “o”, each with a different meaning.

That is an extremely strong claim that I simply cannot support. English is beautiful elegantly designed and trivial to learn compared to french.

Also, if you talk on some mid level (say B1, which takes a LOT of effort for french language), you are not going to get laughed at and ridiculed when using it in UK/US/Australia/NZ etc with english. A very common experience in France when trying to use french (I go there every other weekend, its just across the border). Folks from other parts of former french empire like quebecois or corsicans are much more approachable in this and tolerant. Suffice to say their language variant is often mocked by mainland french too, I think personally parisians are the most cocky ones.

it shows the plural,

un chapeau, des chapeaux -> one hat, hats

But you don’t pronounce it and in your example you know it’s plural without the x.

I would say it’s technical debt but rest assured that the language is alive and will eventually drop the x. Perhaps we will have a s instead of a x first.

It does change sound sometimes based on the following word.