I take a strange (but scientifically informed) view:
Emotions are by their innate nature, irrational things-- where people (or rather, what sets people apart from most other animals) are adapted for rationality*.
Emotions are also very strongly tied to the potentiation and weighting of memory and experience.
Negative emotions especially have very strong potentiation for the retention of memories. This means that the natural state of the human psyche is to accumulate and more heavily weight negative experiences and emotions in future decision making efforts leading to the potential situation where those negative experiences and memories dominate the mental landscape. Eventually, there are serious and real consequences for this.
Since this is a kind of neural-system "tug of war", where the prefrontal cortex tries to downregulate the amygdalar response, and the amygdalar response is backfed constantly into the prefrontal cortex (via memory potential biases), an individual needs to constantly exercise their rational decision making, or they quickly become overwhelmed.
At least for me, being aware of these mechanisms gives me motivation and impetus to mentally disarm negativity, and consciously choose to override the imperatives it tries to imprint on me. This is not the same thing as ignoring emotions-- It is acknowledging the emotions, but also rationalizing that their intensity is the result of evolutionarily vestigial biasing, present in memory storage. The solution is to consciously reinforce positive emotionally tagged memories, while rationalizing the negative ones into submission. Since memories are constantly being re-burned every time you recall and process them, following such a regimen slowly normalizes the bias of the negative emotional tagging, and you experience a more healthy emotional experience when recalling those memories.
The ISSUE, is that most people are neither aware of, nor willing to learn about, nor willing to enact such modulating mental discipline when they find themselves deep in the thrall of a powerfully negative emotional state. This leads to the downward spiral of increasingly negative weighted memory retention, and increased cogitative negativity.
*The prefrontal cortex, which is a decidedly human feature of neural hardware, is believed to be the seat of conscious/voluntary action, and
also plays a very strong role in regulating the amgydalae and their interaction with the thalamus-- That latter interaction is believed to be the physical hardware involved in the emotional tagging and encoding of memories cited above. Humans are pretty unique in having this structure, and this indicates that humans have experienced evolutionary pressure to become more and more rational, in competition with the intrinsic role of emotion and emotional processing in memory potentiation and encoding.