There should definitely be an option for users to disable custom themes on a per-magazine basis. I don’t mind them, in general, but some themes can be hard on the eyes, and I’d like to be able to easily just toggle it back to my own default setting.

This has been discussed in the kbin matrix channels in the past.
An option to see the default or custom magazine theme is something that will definitely be added.

You can however do some cool stuff with it! (best viewed on a darker theme, or tokyo night :) )

This is it! We are a real user-eccentric social media!

People spending a looot of time to ruin perfectly good CSS in the most idiosyncratic ways so you can never look at the page without forgetting for even 1 single second that they did that and wondering WHY they were motivated to do so.

I am personally a HUGE fan. There is a big time collaboration between the ability to run wild in this way, and dynamic communities. Compare MySpace vs Facebook. Also on Team Bold Design: tumblr, livejournal and even reddit (after a big fight when they tried to take it away!).

I do also think you gotta have an option to hide all this beautiful wild stuff. Permanently and globally, for specific pages, and temporarily.