If it ain't broke don't fix it, and the same goes for Toronto FC's playing style when they come home to BMO Field.
Soccer teams can be a little bit two-faced sometimes. There is the home face, the side that is aggressive and attacking, where only a win will do and anything else is a disappointment. Then there is the identity that the team assumes on the road: more defensive, less concerned about victory and more so about getting any points at all.
These two identities are borne of many factors. Home sides are more comfortable in their own building, they have fan support behind them, and an opponent who is often less aggressive.