• Kick/Ban message (server option):
  If someone get's kicked/banned have an option to display a message of why the kick/ban was placed. Could also add a server message of what to do if kicked/banned in addition to the reason (IE "Banned for (time) for (reason) (server message), where (time), (reason) and (server message) is optional). This could sort out some confusion of people reconnecting after beeing kicked etc and causing a ban for doing so.
  
• More detailed disconnect messages (server option):
  "(player) disconnected" could include information like connection issues (timeout, bad sync etc) or kick/ban info. Server could decide which of these messages that should be displayed to the connected players.
  
• Clientside enable/disable voting:
  Let the client decide if they want to participate in voting or not, if not voting have option for No action (No-vote) and Don't add to total votes required for action. Add possibily for type of vote to ignore (kick/ban or restart, end race etc). Some server side part could be added for situations like 19/20 people use "voting disabled - no participation in votes" and 1 have it enabled that shouldn't be able to restart race.
  
• Beeing able to see the ping of other players in connection menu in ms.

Except for the last one (and partily the 3rd) the server side have some power to control if these things should work or not. All up to the server admin to decide. With them disabled it's more or less how it is now.

Good or bad suggestions?

in this order

1 No

2 Already been suggested

3 I dont get what your saying

4 Why?

Adding some optional info to kicks and bans is a good idea. The other suggestions, in my humble opinion, add only unecessary complexity and bloat. 99% of detailed disconnection messages would probably read "timeout" and 99% of users would probably never choose to stay out of voting.