It's not really a problem with flash though. If towers can't normally attack you over a wall, they shouldn't be able to track you there. It makes no sense. Also, you're blowing a 5 minute CD spell because you were dumb enough to tower dive. Either way, it's a win for the other team.
"So selfish them" would be their cry. And, who'd be brave to argue? Doin' what you people need is never on the menu!