Laptop displays are thin and fragile. Rough handling during replacement can easily crack the new display or damage surrounding components like the backlight or display cables. A broken display makes your laptop unusable, and damaged cables might lead to flickering or display issues down the line.
Improper installation might leave gaps around the display, allowing dust and debris inside. Dust can accumulate on internal components, leading to overheating and potential malfunctions. Additionally, a loose display can put stress on the hinges and chassis, causing them to wear out faster.