Icons are there that provide you information who is owner, member, participant, admin. Sorting by "role" seems to me like something which is wanted by "admin" rather than the actual user who wants to find someone by a nickname.

We could think about adjusting icons, but I would prefer not to make a colorful mess out of list of occupants. Moreover, the same list most likely will be used in the case of MIX (same UI) and there is almost no way to detect the role of participant, so I'm not convinced that this is something that people want.

I agree that it may be down to personal preference, but... on the other hand most of the other IMs and application I use pin admins on top (Psi, Telegram, Whatsapp) so maybe they are onto something ;-)

We could think about adjusting icons, but I would prefer not to make a colorful mess out of list of occupants.

+1 for not making it colorfull, but current icons aren't all that useful - icons should make it easier to identify something and current ones are very similar and identifying who-is-who is difficult.

Moreover, the same list most likely will be used in the case of MIX (same UI) and there is almost no way to detect the role of participant, so I'm not convinced that this is something that people want.

I think that exposing "admin" role is quite useful, and if it's not in the XEP then maybe it should be included?