There are better things to buy than antiwards and basing your argument off of a "what if" is retarded.
You say having your team with you is a negative but don't explain why... Another fail argument. Also, why are you dicking around with the buy menu if you know you're going to be rushed? If someone is constantly rushing you should have your autobuy set for what you need so you can wait for him/her. Most rounds in the WCS are decided within the first minute unless it was only shitties shooting each other.
This is probably true on dolls but if you have a vaga or spidy on your team it shouldn't matter. I find your other examples of maps to be falsehoods. Also, a vagabond camping a planted bomb invisible is a very good strategy and requires effective teamwork to overcome. Is it OP? Depends on the variables of how good the vaga player is and how good you and your teammates are.
This would be hard to implement. It means more babysitting and more of a nanny server. For your last point Human is pretty much a counter to anything with bash being as OP as it is.