A few of the major banks, including TD and Tangerine (formerly ING) exclusively use collateral charge mortgages. The one benefit to these mortgages is that the bank registers up to 120% of the value of the home on title against the home, so if you want to access any equity in your home, you do not need to refinance to do so. However that is the only benefit and in my humble opinion, one that is not typically worth the handcuffs that such a mortgage places around your mortgage wrists.
Banks such as TD are not using collateral mortgages because it is in your best interest, they are using them because they make it more difficult for you to not only break your mortgage but even leave at renewal time. This takes away your biggest advantage as a mortgage consumer; CHOICE!