To: PORKASAURUS
One reason for a 90 second shot clock is that it (certainly not you) gives a person the opportunity to chat with the other players without intrudeing on their shot clock.
Some ordinary (certainly not you) persons do not do mathmatics in their head well. Especially when they are rushed, or feel rushed to get their shot in.
Other persons (certainly not you) may be playing on an unfamiliar course. They may even be playing outside of their normal knowledge, or experience because of factors not in their control, wind, green speed, new, or a differant ball and or club.
Lastly, but not least it is game to PLAY! Not a Timed excerise in how fast you can complete a 9 or 18 hole course, with people of a like nature that you enjoy PLAYING a round with, and all the other feel good aspects of a good round of golf, but, (certainly not you).