Charitably, your low expectations are probably the source of your finding them acceptable.

It’s also possible - and you should not take this as an insult, it’s just the way it is - you may not know enough about the subjects of your interactions to really spot how wrong they are.

However the cases you list - brainstorming - don’t really care about wrong answers.

Coding is in the eye of the beholder, but for anything that isn’t junk glue code, scripts or low-complexity web stuff, I find the output of LLMs just short of horrendous.