Learn English – Why does ‘I’m with stupid’ have a positive connotation

It's a sarcastic response.

Taken literally the sentence would mean the speaker isn't already familiar with the situation and wants more information. However it is rarely (these days never) meant literally, and is used sarcastically to mean the opposite. I.e. That the speaker is already familiar with the situation. Its meaning is similar to the expression, "You don't say?", where the speaker is acting like they don't already know, when in fact they do.

The difference between these two expressions however is that, "Tell me about it", has taken on a sympathetic tone over the years, indicating shared misery, whereas, "You don't say?", is an insult where you don't actually care what the person has to say.

There's little in the words themselves to indicate that difference. That difference is simply the connotations those expressions have taken on over time. Tone of voice is pretty critical here, because the difference between a sympathetic statement and an insulting one is simply a different inflection while saying the exact same words.

Nice catch.

My first thought was, why not? Reinvention can be a good thing, if you make incremental improvements (in the world of clichés, I believe that's called building a better mousetrap).

I wondered if maybe the idiom could be used positively or negatively, depending on the surrounding words. For example, I'd consider the expression:

Don't reinvent the wheel.

to be negative, as you describe. However, the phrase:

...continues to reinvent the wheel.

might have positive connotations, suggesting perpetual improvements. So, I looked for some examples. I did find this one:

The artist continually reinvents the wheel — constantly striving for a sublime composition of balance, harmony and refinement.

but the vast majority of the findings were indeed negative:

The idea behind design patterns is to not continually reinvent the wheel.

Moreover, lack of interchange with other teams also often leads researchers to continually reinvent the wheel.

Clients don't want to pay for suppliers to continually reinvent the wheel.

The more I thought about it, the more I wondered if the writer didn't mean to say:

Eminem has continued to reinvent himself, putting his life on display, through a bevy of syllable-heavy, metaphor-driven cuts.

Reinvention of the wheel seems to be a bad thing – a waste of time – but reinvention of self seems to be associated with quests to remain relevant, or on top of your game.

I don't know if I'd go so far as to call your cited usage incorrect, but I don't think an editor's call to maybe strive for a more apt metaphor would be out of order.