The XCU is one thing. The MCU's eventual X-Men franchise is another. You may not agree with the level of seriousness but, as a franchise, the MCU characters have struggled. That doesn't mean they didn't have good days. I think it's ridiculous to say Peter Quill didn't suffer from Meredith's brain tumour when Guardians of the Galaxy 2 showed us he did. Levity breaks tension and makes franchises stronger by showing multi-faceted characters.

The XCU (and movies like TDK) aren't serious, they're dour, and they'd show more growth by embracing some of the lighter aspects of their characters. Consequences work better when there's something to lose, a world is to dark then hope can't be lost. All points are simply being ignored to support the argument you want to make.

However, this topic is actually about the MCU's possible interpretation of the X-Men. Make another one for the debate. Not everything needs to turn into a pissing contest.