Why do cells first transcribe messenger RNA from DNA and then translate messenger RNA to protein? Why not directly translate DNA to protein?

Practically, the cell is unable to translate proteins from DNA as the translation machinery is in the cytoplasm and the DNA is in the nucleus and so the messenger RNA (mRNA) communicates the genetic code to the cytoplasm to be translated. If, however, this could somehow be overcome by moving the translation machinery to the nucleus and set it to recognise DNA rather than RNA, it would still not be an efficient or practical solution for a number of reasons. Firstly, by having an intermediate between DNA and protein, it adds an additional layer of control the cell has over levels of protein. This is hugely important because as effectors, proteins determine a cells function and so to control cell identity and function means controlling protein expression. Secondly, having all the protein machinery in the nucleus, themselves making proteins could make the nucleus overcrowded. Overcrowding of proteins is an issue as it could lead to clumping and protein aggregates - a key property of many diseases including Alzheimers! Finally, DNA is a precious thing to a cell as a change in sequence can lead to change in the coded protein's function. Sometimes this change could lead to cell death or worse to cellular disease and dysfunction as in cancer. To tug huge chromosomes back and forth to generate proteins could cause DNA damage. By first transcribing to RNA, this issue is avoided.