Yes, there will always be some criminals who believe they can beat the odds. Many of them will break into a home no matter what the homeowner does. But, it's my belief that the their number is far less than those who will decide to go elsewhere. The philosophy of most crime prevention practitioners is to introduce as many hurdles between the would-be criminal and target as possible.
Alarm dealers should consider themselves security consultants and act accordingly. Who better to advise the homeowner on deadbolt locks, outdoor lighting, natural hiding places in their yard, the quality of the doors and window, etc.? When I was in business, I worked to became a locksmith because my commercial clients needed to have the mortise lock on their aluminum frame doors rekeyed when they lost a manager. In those days we also used 7- or 8-pin tubular locks with a trim plate, so I'd change them out as well. I got tired of seeing someone else get this work so I learned to do it myself.
I also established partnerships with other trades, such as a carpenter, electrician, and a company that did glass block windows. When I could, I handled all the arrangements, and when I couldn't I tried to solicit a percentage arrangement with the tradesman so he knew how much I had to have to bring him or her into the picture. If they failed to make good on that arrangement, that was the last job I called them in on a job.
When I established Abbott Fire & Security in Canton, Ohio for a large union electrical company in Ohio (between SDM and SSI), I took every opportunity to sell electrical as well, in the form of outdoor lighting, light poles, etc. I sold them right along side my burglar alarms, access control, and fire alarm systems. That did not happen every day, but it surely did from time to time.
Every little thing you do to slow the perp down will serve to discourage him so he goes right on down the road. And yet, you are correct, there will always be those who won't be discouraged in the least. All we can do is hope these guys overstay their welcome by a minute too long :-).
Al