I think BMO has lost interest in Air Miles when it stopped awarding AM based on account balance last year.

The difficulty in redeeming AM travel reward is probably another deterrent; at least this has been my personal experience during the past year or so. It definitely has become increasing difficult when comparing to a few years ago. AM is still insisting on a Saturday night layover and advance booking requirements in most booking situations. For car rental, usually only 100 free km per day are allowed. Redemption at Delta Hotels does not include taxes. Many hotels in the Starwood franchise do not participate, just to name a few issues that I have encountered.

AM may be suffering from the same fate as Aeroplan with too many Miles now chasing after too few reward availability. The "contract pricing" demanded by AM may no longer be attractive to many of the reward providers.