Why must eukaryotic mRNA be processed before being translated?

For the successful translation of the pre - mRNA, the pre - mRNA needs to be modified to mature mRNA.

The pre - mRNA comprises of introns and exons both. The non-coding introns need to be removed so that only coding exons can be translated.

At the 5' end of the pre-mRNA, capping is done and at the 3', poly-A nucleotides are added so that the mRNA can be safely transported from the nucleus to the cytoplasm where the translation will occur. If this step is not done, then the mRNA will be degraded before reaching the ribosomes for translation.