Except no one is centralizing anything. If everyone wants to go to a specific pool and no one is forcing them, they should be allowed to do so.
And tires are not deregulated. You can not just open up a tire shop and start selling tires.
That's kinda funny. You didn't read enough into the centralized Bitcoin argument and too much into the tire one.
The argument goes like this: Bitcoin is designed around decentralization because it is a needed feature for a proper store of value/currency. As such, security has been built around it while keeping in mind that the users will
maintain it decentralized, since their motive for using Bitcoin is that it satisfies the needs of a proper store of value/currency.
You thus have a simple premise: Everyone can contribute data to the block chain. This identifies 2 groups: honest users and attackers. You then need to establish a set of rules that allows you to identify data emitted by honest nodes as valid data, whereas data contributed by attackers is corrupt and should be dismissed. Bitcoin uses proof of work rewarded by coins. Meaning valid work is identified as the most powerful contribution (difficulty and chain length), and it provides more profit than using the same power to cheat the network.
You should understand from this premise that if honest nodes contribute corrupt data, then that data is considered valid. This is the situation DeepBit is creating. The system is built to ward against attackers. If honest nodes partake into a behavior that is corrupt, then there is no difference between honest nodes and attackers, and the system it breached.
This is why DeepBit is a problem, because it concentrates the power of the network into one point, effectively centralizing it. Whoever takes control of that point can inject corrupt data into the block chain at will. Whoever takes that one point down can overpower the network with much less resources than needed otherwise.
No one is claiming for regulations over mining. We are simply warning DeepBit users that for no valid reasons they are centralizing the power of the network, and that harms the security of this network by offering the very tools to attack it to whoever damn pleases. No one here is forbidding you from mining at DeepBit, we are simply telling you that if you don't walk away from that pool, you are artificially creating a great point of failure, all this at the cost of high fees and bad statistics.
Whichever way you look at it, if you purposefully drive yourself into a wall, you can't blame the car.
tl,dr: Bitcoin is built to ward against attackers. If users start behaving like attackers need them to, the security is moot.
Since this attack doesn't permit all that much power over the network, it is expected that no one will attempt it. A profit-seeking person will always gain more by just following the rules, and even someone trying to destroy the system will probably find other attacks more attractive. However, if this attack is successfully executed, it will be difficult or impossible to "untangle" the mess created -- any changes the attacker makes might become permanent.
Yes, that attack can hurt the block chain beyond repair, and right now there is no need to spend a ton of resources over it, since honest users are willingly creating that situation.