[Avamander]

Mobile is often less than that and any hard wrapping looks absolutely horrid. I mean, hard wrapping in general looks disgusting on anything besides an ancient VT-80, but it looks extra bad on mobile. Only tolerable option for plain text is "format=flowed".

[skydhash]

Hard wrapping is nice. My screen is too large for any kind of flowed text so I often have to add the extra margin that is required to get back between 80 and 120 characters. On mobile, you can just rotate the phone.

[jcgl]

Sounds like you need a client whose width can be configured. Rather than imposing arbitrary, non-semantic formatting on all messages.

[Avamander]

I've had autorotation turned off for a decade, I'm not turning it on for your email. It's a bit odd that plain text proponents don't want HTML imposed on them but are okay with imposing this.