Firstly it is necessary to draw attention to the OP statement “students were unhappy with it,” which is a populist sentiment. This sounds suspiciously like equanimity is being used in an escapist sense due to misunderstanding of its actual function as a strategy to be applied only in certain situations.
"He discerns that ‘When I exert a [physical, verbal, or mental] fabrication against this cause of stress, then from the fabrication of exertion there is dispassion. When I look on with equanimity at that cause of stress, then from the development of equanimity there is dispassion.’ So he exerts a fabrication against the cause of stress where there comes dispassion from the fabrication of exertion, and develops equanimity with regard to the cause of stress where there comes dispassion from the development of equanimity. "—MN 101 (Thanissaro)
The Buddha cannot describe the situations in which equanimity would be appropriate, this has to be discovered from personal experience. “Fabrication of exertion” means employing the strategies of right effort, which are specific to the hindrance to which they are opposed and described here:
Equanimity has an agenda, the removal of suffering, and differs from the fabrications of exertion only in that it requires much less effort, and so can be a trap for students.
This shows that attention is an active process:
“There are fermentations to be abandoned by seeing, those to be abandoned by restraining, those to be abandoned by using, those to be abandoned by tolerating, those to be abandoned by avoiding, those to be abandoned by dispelling, and those to be abandoned by developing.”—MN 2
In practice equanimity is rarely appropriate. The analogy of crossing on a raft is used in the suttas, and Hungarians familiar with travelling on water would know that the times when the current and winds combine to carry the raft towards the further shore without action by the rower are few indeed, and even then constant vigilance is required.
Equanimity of energy
A practical way to look at equanimity or equipoise is as a balance point to be attained in regard to the two extremes of sluggishness and restlessness as states of mind, related to the third tetrad, the third foundation of mindfulness and the seven factors of awakening. Beginning with mindfulness of the state of mind, either investigation or tranquillity can be applied depending on what mindfulness has revealed, both resulting in equipoise:
“When the mind is in a low energy mode, there are three awakening factors that can energize it — investigation, energy and joy. And when the mind is in a too-energetic mode, there are three awakening factors that can calm it down — tranquility, concentration and equipoise. This is the basic way I think one works with them. The main point is having the ability to monitor one’s own mind during practice because the awakening factors are not the object of the practice. Instead, with awareness as the foundation, we can bring the mind to a balance point. I see the factors in each group as being interrelated. Investigation is really a sense of curiosity and exploration that is maintained by energy. The investigation is of such a type that it is not pushy and leads to joy. In the other group of factors, tranquility leads to a mind that is concentrated and then leads on to equipoise.”—Analayo