The are plenty of good mua that display html emails well though, so it sounds like your choice to avoid receiving them properly; a choice you're entitled to but not an argument against allowing visually formatting and graphics in emails.
Of course it's my choice,and I've also set up clawsmail to display HTML mail by the press of a button. The point is that I'm not the only one. With plaintext mail you can reach everyone, with HTML mail only a fraction of that.
If you send HTML mails, they're simply more likely to land in the spam folder, where 80% of all HTML mails belong.
>With plaintext mail you can reach everyone, with HTML mail only a fraction of that. //
Any stats on that? I'd reckon you're in 5x9s territory for those that are reachable by HTML mail (vs. plaintext). Also I don't know about other mail clients but Thunderbird has a setting to send HTML email in plaintext too, choose your poison.
For me text based emails are far less common and are more often than not "Hi, my name Lena, I saw your info on Facebook and want to know you well [...]". Indeed the only non-spam plaintext emails I can recall are dev mailing list mails.