In a competitive environment with a time limit, it is important to be able to look at the enemy models to determine their equipment and capabilities. Someone would be really bummed to drive their Land Raider up to your TS thinking they are bolters, only to have you melta the Land Raider. Speaking from my own experience, this especially annoys the more experienced players, who often know your army and Codex better than you do.
That said, here's it broken down piece-by-piece:
Not OK for tournament play.
Some people might not even notice. Some would let it slide, if it was your only army problem. Some still won't like it. Technically not WYSIWYG/using a proxy, so not allowed for Tournament play.
Not OK for tournament play.
Not OK for tournament play.