I was careful with my phrasing when I referenced use for maintenance and utilizing the blockade effect. Lower doses most certainly are useful and often sufficient for detox or withdrawal-cessation but won't provide many of the advantages that clinicians and addicts alike seek.
Many users here will testify that they prefer doses smaller than 2mg SL qd however the reason that larger doses are preferred clinically is because its easier to produce stable plasma levels with once-daily administration and utilize buprenorphine's ability to block the effects of other opioids. You'll notice many here who do maintain on <2mg often split their doses.
In addiction treatment, you want to move people away from use that wears off and move them away from focusing on using substances so its preferred that people take it once a day and establish doses where there is next to little-to-no fluctuation in plasma levels so they never start to feel sick, never feel relief or high from their maintenance meds, etc.
Its not a perfect system for everyone, but this is essentially the philosophy behind once-daily administration of high(er) dose buprenorphine used for maintenance.