I never said I thought being to switch and attack wouldn't vastly change the game, just that the free turn isn't significant enough a disadvantage because its in exchange for a stronger matchup.A free turn is a massive disincentive. The fact that you have to take an attack when you switch in is what creates the distinction between checks and counters. You don't think that the game would be vastly different if you could had no penalty for switching and could instantly attack?
A dead turn is definitionally the penalty for switching and you don't need anything else to penalize it. Switching is not "lazy play". Utilizing a counter is not "lazy play". There is not a larger margin for error without chip damage on switches - incorporating Stealth Rock gives a larger margin for error for offensive pokemon because they don't have to do damage equal to the remainder of a pokemon's HP, they have to do damage equal to the remainder of a pokemon's HP - 12.5%.
The existence of pokemon who are weak to Stealth Rock but still are viable does not disprove that Stealth Rock makes pokemon unviable. It only shows that Stealth Rock does not make every pokemon unviable. That is an unreasonable burden of proof and unnecessary to show that Stealth Rock should not be in the metagame. Just because a state of affairs is not "as bad as it could be" does not mean it is not bad.
You also said that the onus is on pro-banners to provide an argument and we don't need a reason for Stealth Rock to exist. Fair, but we have provided several. Namely - it's no-risk and no-opportunity cost and high returns, and these types of plays should be discouraged in the metagame - it makes a wide spread of pokemon unviable due to large amounts of up-front damage. Without a single reason to keep Stealth Rocks around (and I haven't heard one other than inertia), these arguments are sufficient to ban.
Sorry, I didn't really explain well what I meant by lazy play. What I mean by lazy play is that without the presence of SR a player on the defensive can directly switch their counter in without as much fear of a double switch as they can switch to the guy that counters the new one without being punished for the bad switching. The attacker is also given far more wiggle room when it comes to predicting the opposing switch in and choosing the wrong attack and being forced out by the threat of a KO isn't going to be punished by the wear of SR. This is why Tornadus T was banned, the ability Regenerator meant that it was essentially immune to SR. This when combined with Hurricane's high power and confusion rate along with tools such as Taunt, Substitute and U-Turn meant that Torny T could easily push past its counters throughout the course of the game since it outlasted them. (even hard counters like Jirachi couldn't help getting beaten down by confusion hax and constant switching depriving it of either healing or ever attacking back)
I'm not arguing that SR doesn't hurt the viability of Pokemon, I'm saying that it doesn't hurt enough of them. In other words there are still a large amount of Pokemon that weak to SR that are OU viable regardless of SR being an assumed constant. It's not an unreasonable burden of proof because we don't look at how many Pokemon are not viable or could be viable but at how much currently are. There are well over 700 Pokemon, OU will always be an exclusive list. In fact, BW OU is the larger than any other generation before it. This means that any complaints about the lack of certain Pokemon in OU is completely valueless. We could have even more Pokemon that are ruined by SR and still be considered a balanced metagame as previous generations have clearly shown.
Before getting into this bit I just want to point out that it isn't upfront damage. The effects of SR are spread out over the course of the match with the exception of SR weak Pokemon. (I may have misunderstood what you meant by upfront but if I didn't I wanted to get that out of the way first)
Anyways, I feel that the problem is that the returns aren't high enough. To put it simply, I'm not throwing up SR turn one and proceeding to mow down mindlessly the opposing team much like I can will things like Excadrill, SS Kingdra and even (arguably) Rain boosted attacks. I still have to play a good game and bring a real team if I want to beat somebody of comparable skill, it is by no means a walk in the park just because I have SR up. With something as underwhelming as this (from the viewpoint of suspecting/banning) the fact that it is easy to pull off doesn't mean much at all as that aspect isn't inherently negative. (it is only so when combined with an overwhelming power that thus heavily reduces the need for skill in matches)