Month to month leases and fixed term leases each have their own unique disadvantages.
With a month to month lease you have much less certainty in planning the future income of a property. This may not be such a big deal when you own a building with 20 suites but when you only have one property with one income stream this can be a big problem. Suite turnover can be a problem too as there is nothing you can do to recover lost rent if you need to clean the suite or repair it after the tenant leaves. Sure you can recover the cost of the fixes from the DD but you have lost that time-money that it could have been rented. Plus you spent a bunch of time and money advertising and showing the suite. A month to month lease can be convenient for a landlord who has indeterminate plans in the short term or who is seeking a higher rental rate.
A fixed term lease is useful in that you have locked-in the tenant for that period of time...sort of. The tenant can take off on any day of the week, zero notice and you will still be required to rent it out as soon as possible. You have a duty to mitigate and get the place rented as fast as is reasonably possible. Sure, they are "on the hook" for paying that rent, but if someone is skipping out on rent, it is because they are broke (usually). Can't get money from a stone. Plus a fixed term lease could lock you into a relationship with a professional tenant. There are endless ways a professional tenant can harass a landlord and abuse the system. A pro can bully you around and under a fixed term you will have no choice but to put up with it or sell the property.