Is 做 necessary in the sentence 我不打算做决定 (wǒ bù dǎsuàn zuò juédìng)?
决定 in 我不打算决定 is a verb (I don't plan to decide)

决定 in 我不打算做决定 is a noun (I don't plan to make decision)

'做决定' means 'make decision'


in 我不打算决定 the object is omitted, It emphasizes the verb 'to decide'
我不打算做决定 is a complete sentence. It put emphasis on the object 'decision'.