Why would he use the lasers? ( They aren't actually lasers but whatever). Jotaro would be able to deflect them easily: remember Joseph in his prime was able to dodge them, and Star Platinum is a lot faster than him. Remember the knives actually worked: Jotaro only survived because he hid books in his clothes. In fact DIO would have been able to finish him off had Polnareff not intervened.

Ther is a LOT of inconsistencies between part 1 and part 3 Dio, better to not think about it lol.

I mean DIO was too big dick about his new stand ability toys that he forgot about it probably. I mean he was in a coffin for 100 years too. Even if you're a pro at this game, I'm sure there are at least one or two combos you never utilize cause they're out of the way.