Not sure how a BMW service manager ends up being a "security expert" but as my job qualified me as one, I'll add that the "bad boys" can also bypass a steering wheel device in seconds if they want to; minutes at the most. And they frequently do, but what often pushes them towards particular vehicles and away from others is that they don't like noise that might draw attention to them whilst they are overcoming other obstacles.
It's all about layered security, and a decent alarm system has its place in that approach.
The problem with vehicle manufacturers' own alarm systems is that thieves quickly work out how to bypass them as you say, and because they set and unset with the door locks or lock fob, they are particularly vulnerable. So are aftermarket alarms which advertise themselves on the vehicle and make their installation manuals available on line to all and sundry. So look for a decent and well thought out system that recognises and avoids known compromise routes.
With teams of very knowledgeable hackers making a living in places like Bulgaria and The Lebanon from reverse engineering vehicle manufacturers' own security systems and producing tools and devices that they then sell worldwide via the internet allowing customers with no knowledge of their own to bypass them with ease, I would suggest that a multi-layered approach is essential if you are serious about protecting your pride and joy. Relying on a single device alone, whether that be a physical device or an alarm, is a bit like locking your front door and leaving the back door wide open
