1. Can be disabled in the client
2. Can't really tell people they can't use an item colour no matter how horrible & obnoxious it is However see #4 as it's part of the same client option.
3. Isn't that already a thing when people are going to 1v1?
4. We already have policies about how transparent textures should be in general, however much like 1 you can turn of textures in the client - or you could force lp someone else. Sure you're going to argue it's not ideal, but it can be done.
5. Like #1, #2 & #4, they can be turned off in the client.
So yeah, the majority of this can be disabled client side by people wanting to force an even playing field. Though people are then going to argue that they want their own items/colours to show. You can't force people to not use stuff (#1, #2, #4, #5) so the best way around it would be an option to force the other player to look like uke on your client during game play, they'd look normal during replay & look normal to spectators.
I dunno, you're asking a lot of people with 4/5 of those. It's like saying they can't customise themselves in a game that encourages them to do it.