Is there ever a time when a neutral nature is beneficial?

No.
Mixed attackers prefer +speed or +unfavourable attack- weaker defense.

Anyone else just gimps the atk stat theyre not using or the speed if TR

Story mode, when you're catching a Pokemon you've never seen before. It's safe because at least it doesn't fuck any stat up.
For competitive play, the 10% boost to one stat is always worth finding an area to take a 10% loss in.

>>31531752
The closest thing is a Pokémon like Aegislash or Type: Null, which have great stats except in Speed (and in Type: Null's case it holds an Eviolite)

>>31531752
I wanna fuck that breeder

>>31531892
>i wanna fuck that breeder
>not breed with her
One job anon