Why every release is a "ThRilleR"

I bet you too might have experienced this. Thrillers have

• Tension
• Suspense
• Excitement 

"A thriller is villain-driven plot, whereby he or she presents obstacles that the hero must overcome" - wikepedia

I agree with the above statement from wiki. Now you need to fit in the characters in the above statement.
Don't take it seriously ;)

I always keep thinking, why this happens?

Improper planning
Lack of motivation in team
Lot of changes
Unexpected deadlines
Unreasonable expectations
Lacking a good leader
Too much commitment
Casualness

Add on, if you can share from your experiences

"Paani da rang vekh ke, akhiyaan cho hanju rul de" = "Seeing the color of water, tears roll down my eyes" -AK